Hello Yeti. It is nice to meet you. We have an Interest Check section that people note their interest in the proposed RPs. There is a general section and one for each level of RP we do here. They are organized by standard of writing. If you are unsure which you would fit into take a look at the IC threads to determine that for yourself. From there it is up to the GM of the RP how they want to accept people, so you would need to ask them for that information on a per RP basis.
If you have any other questions feel free to PM me or use the Ask a Comrade if you have further issues.
If you don't mind me asking, what sort of RP's did you do on Gaia?