Steve is one of those male names I overused for awhile because I don't know any Steves particularly well. I have several Steve acquaintances, but no overwhelming association with the name. So Steve is safe, as names go. Dave and David are also safe, because I know too many of them. At any moment I have a default David, both generally and in a given conversation, but I have enough of them over time that I can use it without immediately associating with someone specific. (In a given conversation: Dave Orser is not my default Dave, but if I'm talking to Heathah and she makes reference to Dave or David, I will assume she means her spousal unit, the father of her children, etc.)
The exceptions are what's really confusing me. I almost never call timprov Tim, but he is enough a Tim for me that I couldn't use the name in a story without associating it with him. But the same is not true of Timothy. Someone who went by Timothy would be a very, very different person. Ditto Kev/Kevin: I couldn't name a character Kev because of greykev, but Kevin is a more distant name, because I only call him Kevin when he puns badly or does something else requiring multiple syllables ("KevIIIIINNNNN!").
I used to think that meeting more people would make this more problematic, but I keep meeting people with the same names over again -- moving, say, David, from "my godfather" to "lots of people I know."
Still, guy names are hard, because a character named Percival in a modern setting is going to have a lot of grief in his life, but I can't name the same guy Mark, because markgritter is already Mark.
How do you do this, those of you who do this?