I reread the opening post. We’re expected 3 posts a week?
At least 2 a week, if you want to have a crystal. More if you can. Post length is not as important. There is nothing wrong with being a regular character, if you don't to post that much.
Mainly, since our stories will revolve around crystal holders, I want those writers to be responsive when others mention them in their posts.
However, as the blue crystal holder (the crystal of loneliness, if you will), you probably won't have lots of people trying to interact with your character.