I'm fairly new to the forums and I'm not sure if this has come up yet. How many GMs out there also have a PC?
When I first started GMing my group I didn't, as I was new to the game as well and thought it would be too difficult to do both. In the session before last, our group had finished Long Arm of the Hutt and it felt like a good time to let anyone change their character, as well as add a character of my own.
So far I haven't found it too difficult to do both. I try and keep it fair by having the rest of the group take the lead and my PC tags along for the ride. My PC doesn't make too many decisions but will assist when asked by a fellow party member. At this point, keeping PC knowledge from GM knowledge hasn't been too difficult, and the rest of the group seems to enjoy me playing a character as well.