How big is your closet?
Of course the type of closet door you have depends in large part on the size of your closet. If it's a wall closet - very shallow - then of course you'll need a different type of door then if it's a walk-in.
The four types of closet door, therefore, would be the simple panel door that opens outward and lets you into the walk-in closet, bifold doors that let you view your wall closet, and the sliding doors which could be used for either version, depending on the length of the closet itself. The accordion door is also a choice.
Bifold doors would allow you to use over-the-door system to store shoes, for example - which would not work with a sliding door. Sliding doors can look more attractive than bifold doors, however.
Matching or contrasting colors?
Of course the first thing you'll have to decide about the door is its color. You'll need to find a color that will match your bedroom walls, or set it off in a striking manner. If you'd like to give your bedroom the illusion of greater size, than you'll want to get mirrored doors. And for that really elegant touch, you can even get sliding frosted glass doors.
And you'll have to give some thought to the future, of course. If you like to change the color of your bedroom every now and then, you won't want to have to change the closet door as well because it would clash with your new decor.
Vinyl or wood or what?
And what should your closet doors be made of? You've got a lot of varieties to choose from: stamped steel, hollow core, super-thin wood, or solid wood. Solid wood doors give you the most variety in their design, for you can have them hinged, folding, sliding or with pocket applications. These doors can have flat panels - to which you can affix mirrors or fabric, or louvers. (Kestrel Wood Closet Doors is one company that offers solid wood doors of high quality. They also do custom doors.) For mirrored closet doors, Fort Glass (fabricators of Stanley Mirror Doors) are one provider out of several that you can investigate on the web.
There are so many choices that you won't want to rush into your decision. Take your time investigating sources on the web, visit such stores as Home Depot or Menards or the specialty stores in your area. You can also take advantage of open houses in housing developments to go in and visit these houses and see the way those closets and bedrooms are designed. You'll then be able to make an informed decision.