I find that when sitting,it is best to place your guitar propperly (well, like the classical guitaring way) with you axe on your left knee (if you are right handed) and your left foot on a little foot stool, or your case or what have you...the neck will then be slanted upwards at a roughly 45degree angle...not only does this look more professional, but it also feels more similar to the way your guitar does when you are standing, so its much easier to adapt to standing play...if you get my drift.