Well probably the most important thing is that you name what genre it is in the title for example. If you were trying to start a Dragon ball z Rp where you can train and fight each other you should add [Anime, Action Rp] to your title.

Here a short list of tags you might use.
Romance - For dating and Romantic Rps.
Action - For Rps That involve fighting.
Sci-Fi - For threads that involve Space, Aliens, or anything else in Science Fiction.
Fantasy - For more magical Rps, Usually with elves and other mystical creatures.
Realistic/Slice of Life - For Rps that involve everyday things like school or a bar.

Also, no Adult themed Rps. You're free to request a 1on1 Rp in the request thread but save any juicy details for PMs please.