I would start by reading the stick topic in the forum called The Idiot's Guide to RP. For someone new to the idea, its a great start. Next, come up with a story for one of your characters. Who are/were their parents/siblings, how did they get their powers, what's their favorite food, color, outfit, what are their hobbies, give them a personality, and every time you team or are standing around, try to talk in character, instead of 'these guys are only green, lets get the glowies and go' maybe 'these goons aren't important to mess with, lets just find the crates of supplies and get out of here'
If you just want to see some RP in action, watch the threads here for the big events, there is always RP going on at those...like I believe Justice Girls and American Legion are putting on a big party next weekend.
Playing on Virtue and being the main recruiter for 3 VGs, I am often asked if our VGs roleplay. I'm beginning to feel like there's an aspect of the game that I'm missing out on. I've never been much into roleplaying but I'm willing to learn. I would like to find a few experienced roleplayers to help with organizing events and to walk me through becoming a roleplayer. All of our VGs are themed by AT and when GR comes out we intend to incorporate hero ATs into our structure. Our VGs are in order by when they were created: Wolves of the Black Moon (all VEATs), Voodoo Masters of Virtue (all mm's), and Corrupted Inc. (all Corr's). You can find me in-game via my global @Ghoul Slayer. I also play on Freedom as well and I alternate my days between the 2 servers.