You take good care of your skin, and you want to take good care of your waistline and your health, too. Like many others, you’re considering turning to a personal trainer to get rid of those unwanted pounds.

But what should you know before shelling out the dough?

1. You’re wasting your money if you don’t change your diet.

If you’re already eating a sensible diet, controlling your portions, drinking your water and concentrating on the basics then exercise might just be the last ingredient in a successful weight loss formula. But if you’re still eating Doritos for lunch and pizza for dinner then you might want to focus on fixing your food before you pay big money for a trainer.

Sure, you’ll still get some benefits from the exercise that you do. But weight loss probably won’t be one of those benefits. Which, in turn, is rather de-motivating, meaning you’ll probably drop your program. That means all the money you put into all that training is going to be wasted.

2. Do your homework.

Almost anyone can call themselves a trainer. Some states have incredibly lenient licensing requirements. Some trainers have studied their craft for years. Others like to lift, woke up one day, and decided that this was their new career path.

So check that person’s certifications. And check that person’s references. And then? Check again.

One easy way to look up the trainer’s certifications, and to compare them to others in the same profession, is by visiting http://www.ideafit.com. You’ll be able to search by city and get some idea of what is out there. And sites like Angie’s List do include personal trainers now, giving you an opportunity to read over the trainer’s reviews.

3. Ask about training style and philosophy.

If you already know you don’t work well with the “drill sergeant type” then  you need to rule that person out before you write the first check. Spend some time talking about the trainer’s approach. Ask what sorts of exercises he has planned and what pace he thinks is appropriate for your age, fitness level, and weight.

Make sure you interview at least three trainers before making a decision, if only to get some sense of the ranges of philosophies and options that are available to you.

4. Make sure you’re serious.

Personal trainers rarely come cheap. Before you shell out big bucks make sure that you’re committed to your new fitness goals.

How can you do this? Set yourself a goal. Make yourself go for a walk every day for a month before signing on the dotted line. Or sign up for a less expensive online program, like Hulu’s “Daily Burn.”

If you get through a whole month you’ll already be in the fitness habit, and you’ll have more confidence that this is something that you’ll be sticking with. As a bonus, you’ll be in better shape to tackle the training, too.

5. Prepare for pain.

A new exercise routine always brings some pain, stiffness, and soreness with it. If you’re mentally prepared you’re less likely to allow that pain to derail you.

You should take the time to get physically prepared, as well. Make sure you order some Extreme PR so that your new training regime doesn’t destroy your whole day, and so that you can continue to train even after the going gets tough. You’ll get better results–and you’ll be happier, too!