Write yourself up a character sheet, that clearly defines your powers & limitations. No sudden “I pull out the secret weapon omega almighty god sword that I had no indication of having before”. This doesn’t mean you can’t improvise in combat, just that you don’t gain any sudden new powers. When joining the RP, also send this to the DM, so they’ve got a good idea of your strengths & weaknesses. Speaking of weaknesses, and character flaws; have them. Nobody likes the perfect flawless hero who can defeat any enemy with his hands behind his back and his eyes closed. Even if nobody else is, reach out & talk with the other characters when you have a chance. You’re a part of a group, and interacting with that group is the fun part. And finally, remember you’re just one player in the game, not the star of the show. If you see someone having their moment, let them. Don’t feelthe need to be at the center of every event. It’s okay for the others to get their time in the spotlight. But most importantly, you’re all just there to have fun! So do that!