The term "cosplay model" brings to mind a career, but it in fact usually refers to a hobby that may or may not coincide with one's job. Cosplay, which is a contraction for costume play, is a popular pastime in which the cosplayer dresses up like a fictional character. For most people, cosplaying is a hobby, and one that can get quite expensive, but a there are people who manage to make money from that hobby.
Choose a character whose outfit will look good on you. To be blunt, don't wear a revealing costume if you can't pull it off. Your costume will look better if you actually look like the character, but it also needs to be someone you'll enjoy cosplaying as.
Make your costume; don't buy or commission it. Your costume will fit you much better and be far more appreciated if it's a complete original.
Attend as many conventions as you can. This is where you'll spend the majority of your time in costume. Keep up with convention schedules and spend time going through related forums. Forums dedicated to your convention may list unofficial gatherings that aren't in the official schedule, such as meetings for photo shoots.
Be as active at the conventions as you can. Pose for pictures in the halls and attend or participate in events like cosplay contests, panels, and games like cosplay chess. Find out if there's a fashion show at the convention you're attending, and participate in it if at all possible.
Anime conventions are held all over the world; California alone had 11 anime conventions in 2009, as well as other anime-related conventions. Most conventions allow anyone to participate in their events. Check the rules for participation in events at your convention, as they may differ from one convention to another.
Making Money Cosplaying
Make and sell cosplay items, such as wigs, accessories, props, clothes, or entire costumes. Sell your creations on existing auction websites or on your own website, or become an exhibitor at a convention and sell them there. Different people take different levels of interest in their hobbies, so there are plenty of people who want to buy costumes instead of making them.
Look for jobs that pay you to work in costume, such as for promotion at venues like Comic Con or E3 (Electronic Entertainment Expo). However, bear in mind that these will be few and far between and won't constitute a career.
Attend conventions and participate in events even while you're working on these steps. Hand out business cards at conventions and try to get your name out as a businessperson. Even wandering aimlessly through the halls and posing for pictures can give you a degree of recognition in the community.