I am starting a Pathfinder campaign that uses material from Serpent's Skull and Age of Worms, part plot-driven and part sandboxy.
Experience with the rules does not concern me overmuch, but you should be willing to learn them. I prefer players who like to roleplay, develop their characters, and focus on the game, who take time to formulate plans and strategies. But I also like action, monsters, and combat - so intelligent character builds are good too. Willingness to work within the framework of the campaign and cooperate with the other players is crucial.
All that said, we do this for fun. Half the fun is finding humor in unexpected places, and sharing asides with like-minded friends! Game on!
I've been playing d20 games since they came out, and D&D since, gads I'm old, 1986 or so. I've played and run Pathfinder, D&D, TMNT, Palladium, and Call of Cthulhu. I was really into White Wolf's Storyteller games and LARP in the angst-chic 90's, but these days I prefer more heroic campaigns. As a player, I'd like to get into a Pathfinder or a Star Wars Saga Edition game very much. I'm also interested in D20 Modern and other D&D settings.