My greatest failing is something I'm still probably kinda doing but trying to get away from.  Tend to make characters that just kinda go along and don't really push events along.  Sometimes it's well intentioned so as to not take too much control of the pacing, but often times it's just not really fully participating.

That and trying to join a few RPs, Storm/Poo/Hank's Elder Scrolls one and LordWraith/Henry's Amalgam one come to mind, but failing to come up with an adequate character.