When Susan Johnston decided to save a few bucks by reattaching her vacuum cleaner plug to the cord, she didn't realize she was playing with fire.

"I was trying to save about $45," says the 30-something production vice president from Burbank, Calif., who consulted a do-it-yourself book to handle what it called an easy repair. Following the instructions, Johnston opened up the cord, slid the wires under the screws, put the whole thing back together and plugged it into the wall.

Immediately, there was a pop, and flames shot 3 feet into the air.

"My wall was black, my vacuum fried, and I had to hire an electrician to rewire the plug in the wall," says Johnston, who spent about $350 in the aftermath of her disaster. "The electrician said I was pretty lucky; I could have gotten electrocuted."

With budgets tight, more of us are strutting our autonomous stuff by tackling projects on our own. Unfortunately, like Johnston's vacuum cleaner, some intrepid do-it-yourselfers are getting burned, shelling out extra cash or suffering injuries when a project goes south.

Here are some of the most common frugal failures — and what you can do to get it right.

Budget beauty

Coloring our own hair and painting our own nails will cost the beauty industry about $500 million in 2009, estimates market researcher IBIS World. Sales of home hair coloring supplies are up 19%, and electric hair clipper sales are expected to grow 11% this year.

But cutting costs and cutting hair don't always mix.

"We've had a couple of people who've asked friends to do haircuts in preparation for major events like a wedding or class reunion," says Margery Huff, the director of hair care retail at Gene Juarez Salon in Seattle. The result of saving $60 on a cut? Hair extensions — "because the haircut got so short while they were trying to make it even" — starting at $1,200.

More people are trying to do their own eyebrows at home, too, Huff says. "Sometimes, the wax will get too hot, and they'll burn themselves. Other times they'll go too thin and will have to pencil their eyebrows back in."

Rather than walk around with scary hair and uneven eyebrows, make budget beauty work for you:

• Get closer to nature. If you can't skip the salon, at least go with a look that requires less maintenance and less money. "Instead of taking your hair from dark brown to light blond every four weeks, go with ... a few bright accents, so the maintenance is stretched out," suggests Huff. Root touch-up kits ($4 to $10) are a great way to make color last.

• Bargain hunt. Local beauty schools often offer drastically discounted services. Look for specials when new salons open. And make sure to ask whether your favorite stylist will offer complimentary bang trims (many do).

• Learn the ropes. If you're going to do an at-home cut, do your research. Have a friend teach you, or tap YouTube or your local library for instructional videos. Get the proper equipment: hair scissors, fine-toothed combs, electric clippers. Betsy Talbot, 38, of Seattle says her husband thought he could save by cropping his hair short with a beard trimmer. He wound up shaving a 3-inch bald patch onto the back of his head. "You definitely have to get barber clippers," she says. "And learn to have patience." Talbot says they've saved $200 over the past nine months.

• Start small. When it comes to home hair color, start with shades that are close to your natural color and do a test strip beforehand. For home waxing, think mustaches and eyebrows rather than bikini lines and legs. And always, always, always read the instructions.

• Remember, it's not forever. A good home hair coloring job may not look as good, but it's not the end of the world. "I was spending about $200 for a cut and color every eight weeks at the salon compared to a $10 box of Feria at home," says Vanessa Torres of Beverly Hills. "Does it look as good? No, but it's absolutely fine for right now."

Mr. and Ms. Fix-It

Home repair and maintenance is another big area where we're taking matters — not to mention hammers — into our own hands. A third of those planning home projects told Angie's List they were going the DIY route. Nearly a quarter of Americans said the same in a Time magazine poll last spring.

But not everybody is a Bob Vila when it comes to home repairs.

A survey this spring by Angie's List found that one in five DIYers had to call in a pro to finish a job and/or repair accidental damage.

Glen Berkwitt, the owner of the Mr. Handyman franchise in Seattle, says he's seeing the same trend: The number of calls he and other franchises in the Seattle area have received over DIY jobs gone wrong have tripled in the past six months.

"People are attempting to do more things by themselves, but they're not technically equipped or competent to do them," Berkwitt says. "They'll borrow their neighbor's nail gun to try to install crown molding and puncture a pipe in the wall. Or install a pedestal sink in the bathroom and not affix it properly to the wall. Their 3-year-old will do a pull-up on the edge of the sink, pull the bowl off, and it'll smash, break the supply lines to the hot and cold water and cause a geyser."

Installing that pedestal sink by yourself could save you $700 in professional fees, According to DIYornot.com — but get it wrong?

"Pedestal sinks can range up to $1,000, then there's the cost of the plumbing fixtures and the materials you've destroyed, which can cost $600 to $800," Berkwitt says. "The cost of a plumber or contractor to come in and fix the damage would be another $1,000 maybe. And then if there's been flood damage — damage to the floor and to the ceiling and walls below — you could pretty quickly get up to $10,000 in repair costs."

Adding insult, there might be injuries, too.

One in 10 home-improvement buffs over on Angie's List admitted to a home repair accident. Consumers made up 40% of nail gun injuries treated in emergency rooms between 2001 and 2005 (ouch!), and nearly 165,000 ladder injuries are treated in ERs each year.

How can you do it yourself at home without losing your shirt (or a finger)?

• Be honest about your abilities. "Think of the worst-case scenario," advises Leah Ingram, the author of "Suddenly Frugal: How to Live Happier and Healthier for Less." "Take the risk factor into consideration, all the stupid mistakes you could make."

• Start small. Forget plumbing, electricity or roofing projects. "I suggest people start with maintenance of things like their car, their home, their bicycles, their appliances, rather than doing repairs and remodeling projects," says Jeff Yeager, the author of "The Ultimate Cheapskate's Road Map to True Riches." "And don't get overly ambitious. Never start more than one project at a time. That's a common pitfall."

• Watch for hidden costs, including your time. Tyler Spurgeon, 27, of Salt Lake City went the DIY route with his kitchen cabinets, forgoing Home Depot's $8,000 estimate, which included installation, by ordering online and handling the installation himself. Quickly he ran into unexpected expenses: taxes, hidden fees and the cost of special tools like a table saw. The worst part? The 15 kitchen cabinets came with absolutely no instructions. "The cabinets were originally $5,000, but (by the end) I was looking at about $7,000," he says. Another hidden cost: his time. All told, the project took him more than two weeks. He thought it would be done in two days.

• Learn from a master. Yeager encourages novice DIYers to turn to friends and family who have home repair experience for their training. Spend a day observing them tackle a project at their house or hire professionals to do something for you and watch them work. "It won't cost you any extra to watch," he says. "And if you just pay to have it done, you're not getting the most for that money."

• Study up. Workshops, classes and instructional DVDs and videos are also available — and often free — through libraries, community colleges, YouTube and home improvement stores such as Home Depot and Lowe's. Good Web sites include GardenWeb.com and John Bridge.

Going Green

We're clipping not only our hair but our lawns, too. About 18% of Americans cited yardwork as an area where they're bent on saving green, said a Time magazine poll in April. It's cost the landscaping services industry between $2 billion and $3 billion since 2007.

Anthony Moran, the general manager of Superior NW Tree and Shrub Care of Woodinville, Wash., says he, too, has seen more people opting for DIY yardwork and tree care. Some of them ask for a quote and then decide to do the "easy stuff" themselves. Others try to take it all on and then call in the cavalry when things go south.

"I would say we're getting a 10% to 15% increase in people saying, 'Can you help me fix this?' after they were pruning it themselves," Moran says. "We just had a lady who tried to prune her own rhodies and butchered them. Halfway through, she called us and said, 'I don't think I know what I'm doing.' "

While messing up pruning may be merely aesthetic (the damaged rhodies will look horrible for a while, but they won't die, Moran says), DIY tree care can carry a much higher cost.

"We started tracking consumer fatalities and injuries about a year ago because they were getting so out of hand," says Tchukki Andersen, a staff arborist for the Tree Care Industry Association. "These are people who are trying to save money, and they don't have the skills or the equipment, and they end up in the hospital."

After putting safety first, what should a cost-conscious consumer keep in mind when it comes to DIY lawn and tree care?

• Know your limits. Most people can handle mowing lawns, but pruning a delicate and expensive tree is both literally and figuratively above most homeowners' heads. "A Japanese lace leaf maple can cost between $5,000 and $8,000 to replace," says Moran. Just as important: your health. Johnston, the intrepid homeowner who tried to repair her own vacuum cleaner, saved hundreds by doing her own brush clearing last year, but the pollen and dirt wreaked havoc with her allergies. This year, she gave her lungs a break and hired a gardener.

• Negotiate. Although Johnston went with a professional to clear her hillside, she was able to negotiate a better deal. "I called the $700 gardener and offered to pay him $500." He went for it, and Johnston was able to breathe easier.

• Divide and conquer. Most reputable tree services will offer free estimates, Moran says. "There's nothing wrong with calling us up and asking us to come over and talk to you about your yard," he says. "Most guys will offer up some free advice. You might be able to handle the little trees and have the pros do the big trees."

• Embrace the tree of knowledge. If you do decide to go DIY, take advantage of the information compiled by the International Society of Arboriculture, Plant Amnesty or the local library. "Spend $50 on a community college course that will teach you pruning, or shell out a few bucks at Half Price Books," says Moran. "Educate yourself so you don't devastate what you have."

Granted, there's plenty that can go right (big savings) and go wrong (flooded basement) when you hop aboard the DIY train. But even if things should derail, Ultimate Cheapskate Yeager says there's still something to be gained from the experience.

"My odd contention is that it can make you a better person," he says. "You can learn to do something for yourself. And if it goes wrong, you'll still get some joy out of telling people about it. What fun would life be if you didn't get lost along the way now and then, if you didn't have an unexpected adventure?"

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