Don't take over other people's RP characters (unless they're okay with it).
In general, you should 'conveniently omit' context that denotes your character as "the player/the one" from in-game, and, rather, generalize events, so as to maintain a shared semi-non-conflicting RP-thread continuity. Will require your creativity! [Notes: It is not to say your character didn't engage in specific episodes/events, but not to specify they did either.] [Exceptions: Large scale events, like fleet battles (i.e. The Iconian attack at Earth, or general Na'Khul alerts) are encouraged to mention, but may still require some generalization. Use your best judgement!]
The RP is in a perpetual state of the year 2410 (until the game moves forward).
Types of play (can combine more than one):
Integrated with story - Join other Captains in solving an issue
One off/or more than one off - Like a mini fanfic, make a short stop to replenish supplies, drop prisoners, etc.
Side story - Posts about stuff your Captain is dealing with. Can work well with "Integrated with story".
(That's all I can think of right now. There's probably more ways.)