Maybe you've decided to make swimsuit season your friend this year, or you just want to lead an all-around healthier lifestyle. Whatever your motivation for joining a gym, finding the perfect match can be a challenge. Here's how to stack the odds in favor of finding a fitness club that fits you. Location, Location, Location "The most important factor is convenience when it comes to location," says Bill Howland, director of research at the International Health, Racquet & Sportsclub Association. Eighty percent of a club's membership generally comes from within a 10- to 15…