If you are concerned about the level of the game you are looking to join- send a PM to the Admin of the game if you have questions. Most will be pretty helpful if you just ask them what is expected out of a player. Some are even willing to help you "rise up" to the level of the game if you are feeling like it may be too advanced for you.

It can also help to read through the Overview. Usually this will give you an idea not only about the game, but about the expectation of the GM. The Overview can set the tone of the game and the "level" of the game- especially if you see what is expected of character design.