People spreading themselves too thin.... You'll get a group together, everything is going great. Then people start joining other Rp's or starting one, then you get the message - No time to post - but you see them posting trying to get into even more Rp's.

I have no problem with people being in as many rp's they want but if it spreads you too thin, cut back. Don't let all the rp's you are in suffer because you're taking on more than you can realistically handle. 

Trust me, quality beats quantity any day of the week. You'll enjoy it more, stress less and burn out less often.