20 Things You Probably Don't Want for Free

Let's say you win a free vacation, but then everything goes wrong: The company booked the wrong flight. The hotel doesn't have the reservations. And the destination itself turns out to be a nightmare. Is the vacation still "free"? Getting goods and services for free might work out fine most of the time, but if they end up costing time and money over the long term, it's time to consider investing money in those things upfront. To help avoid hassle down the road, we collected 20 things you probably don't want for "free."

Related: 18 Ways to Go Broke Trying to Get Rich

Acupuncture might be ancient, but practitioners need modern licenses. People who offer free acupuncture services might not be certified, leaving patients more vulnerable to its risks -- infection and injury. When trying acupuncture, make sure the person inserting needles charges a respectable rate for the right reasons.

If you're going to invest in one aspect of a wardrobe, choose work clothes. Free clothes tend to be hand-me-downs that probably aren't the perfect size, which is bad for jobs that require a professional look and those calling for durable clothing. If you must wear free clothes, stand firm on finding some that fit perfectly.

Getting workout tips from friends is usually no big deal. But bad advice on how to squat or bench press heavy weights could cause serious injury. To get in shape, consider hiring a personal trainer for a well-thought-out session. Some gyms offer free personal training sessions for joining.

The definition of a great friend is someone who will help you move. (Coincidentally, great friends also drive trucks.) But moving isn't fun. It's often sweaty, annoying work, and there's a good chance an amateur's going home with a thrown-out back after breaking something valuable through clumsiness or lack of proper packing materials.

Learning a foreign language can help people stay safe and get the most value out of traveling abroad. Although there are a handful of interesting free language resources online, true fluency is best achieved by finding a teacher who can help with practice through actual conversation.

Shoes are arguably the important part of a wardrobe. A bad pair can cause blisters, cramps, and back pain. Hand-me-down shoes in good condition might be fine, if they're the exact size. If they're not, toss them and invest in well-made shoes that fit well.

Getting a free tattoo from an amateur using dirty or faulty equipment could result in serious infection (and bad, permanent art). Laws vary by location, but tattoo artists are typically required to obtain a license -- and certified artists are unlikely to work for free, or use dirty equipment.

All students need practice, but it doesn't have to be on you. Getting a free haircut from a cosmetology student might seem like a steal, but if the student messes up, fixing that botched hairdo is going to cost money and time. It's better to find a good stylist and stick with them.

Basic rule of thumb: Don't accept free services that involve someone else putting their hands in your mouth. Some dental hygiene colleges offer free teeth-cleaning services by students, supervised by dentists. Sitting with an open mouth for 30 minutes is uncomfortable, and might get painful despite the savings.

Some simple car maintenance can be DIY, but accepting free car repair is risky. It might be impossible or least awkward to hold a mechanic financially responsible for damage to a car that could necessitate further repairs -- especially if that mechanic was a friend.

Up-and-coming performers are sometimes willing to play gigs for free to get experience. But for a wedding or other live event, established professionals charging standard rates are safer. They'll likely show up on time and perform well, with no technical problems.

Free samples handed out by makeup departments to promote products is fine. But a free makeover by an unfamiliar sales associate? Think twice. It won't be worth it if you're horrified by your appearance.

Companies who award "lucky" customers free vacations might not get involved with logistics, leaving customers to navigate potential pitfalls with airfare and lodging. Even the destination might be beyond control. And the whole thing might also be a scam, U.S. Postal Service inspectors warn.

Getting a new glasses prescription can be annoying. But free glasses aren't the solution. They're unlikely to fit correctly, and there's no guarantee the prescription will match -- and bad prescriptions can cause migraines and dangers while driving. Glasses can be found pretty cheap, anyway.

Conventional wisdom holds that a good mattress is worth the investment because people spend a third of life in bed. Old mattresses do get given away, but they might not match your needs, and might have bedbugs. Cheapism has advice on quality mattresses that won't break the bank.

Landscapers typically don't need to be licensed, so it can be difficult to know the lawn's in good hands. Professionals will charge an industry-standard rate that should mean better quality -- and no punctured buried pipes or severed wires in the backyard.

People who might benefit from psychotherapy sometimes try to talk through issues with loved ones instead. There's nothing wrong with getting comfort from friends and family, but they're unqualified and likely unable to provide an objective assessment of mental health.

Accept free electrical work under no circumstance. Professional electricians complete technical school and undertake apprenticeships to obtain licenses and certificates, in part because the job can be dangerous. Shoddy electrical work can cause fires, electrocution, and costly repairs.

Simple clogs or leaks can often be fixed with amateur plumbing skills. Anything beyond that should be worked on by highly trained professionals charging a reasonable rate. Unqualified amateurs run the risk of doing shoddy work that can cause malfunctions that are costly and, well, disgusting.

Getting free Wi-Fi from unsecured networks may save money in the short term, but could cost a fortune over time. Unsecured networks don't afford the same protections as encrypted networks, leaving personal information such as passwords and credit card numbers more susceptible to theft.