On the whole, I try to shy away from extremely socially savvy or subtle characters. I could nail the personality type, but I've got pretty bad ADHD and would just fail miserably at subtlety, so I play to my strengths. Also, I seem to be almost exclusively playing women, which is odd. But I throw in all kinds of random stuff- Bast's mortal name of Sarabi, their fondness for felafel and Indian food, 4chan's hatred of Avatar (which, if you look at EncyclopediaDramatica, is canon :P), Lady Gaga, their favorite TV shows, or Paparazzi's near heart attack at the thought of redoing Khan.
Paparazzi: Mmm, she's a lot of my bad qualities isolated. (That's a common thread here.) Sadism, nosiness, lack of boundaries, never knowing when to stop and shut up- I take those small traits in me and blow them the fuck up. The biggest thing of mine that she has is her tunnel vision, which makes it easy for me to concentrate those other traits in her. When she focuses on something, she doesn't let it the fuck go, even if she's got no good reason for it. But I have to force myself into a bubble-head mentality with her, which comes easily on some days: it's all my perkiness and chipper, bouncy energy.
4chan: Stunningly like Paparazzi, actually, except with absolutely no brain-to-mouth filter. What he has of me is my first urges- when I see a post and my first impulse is to reply immaturely to it, that response would be 4chan. The process of going "No, Amy, Bast/Terpsichore/whoever has something real to say to this" doesn't enter into it as much, since /b/ itself is so unfiltered. When playing Chris, I slip halfway into "Internet troll" mindset. When playing Allison, I pretend that I'm arguing with someone on the internet about some moral issue of great importance- can't you see that the casting of the new Star Trek movie is completely off-base, what's wrong with you you monster- oh look it's kittens- oh god it's a video of a crying baby brb Volterra. With Chris, I have to channel my arrogance, which is a lot of what I used to project outwardly (and still do, to some extent). With Allison, it's almost harder, because I have to draw on something much more vulnerable and broken.
Sonneillon: Base urges and perversity. We don't agree on stuff at all- Sonny/Sonja's views on sex and gender are completely and utterly fucked, but I find it so interesting to play with her views on gender as a means of spreading hatred. I toyed with being a women's studies major and took a couple classes, so that's where some of that comes from. And just, y'know, the fighting urges and combativeness that I can be good at. She's harder to play than you'd think sometimes, because I have to remember to use subtlety, which is a skill I'm still learning as a person, but my RP is actually, um, helping me with that. That said, I love playing Christians- I'm a humongous religion nerd who had 12 years of Catholic school, so stuff like Sonny's argument with Saint Sebastian is like sweet nectar of the gods to my brain. Don't be surprised if I'm playing six Christians by 2011.
Jessica: Ah, my mortal. She's like me on my bad days, or when I was younger combined with some of the good qualities of my significantly more responsible friends. She's got the comparative gentleness of me now, and some of the unbroken, still-strong vulnerability of my high school self, with the sense of chomping at the bit or feeling trapped. And sometimes I even pull on the divorced-child feeling, when she's torn between loyalty to her boss and the fact that her boss is a complete bitch. For instance, when she was conspiring with Arachne, it was easy enough to play but some of that came from the divided loyalties feeling a person gets from, for instance, divorced parents. Jessica wants to be a writer, which is one of my ambitions- but it's been thwarted, which I see as a kind of universal thing. Also? most of her comes from my experience working for a hell-beast boss at McDonald's. XD