I usually hunt in fairly thick areas or along the edges of wide trails or small fields, anywhere multiple trails converge and where I've found recent sign. If it is in the morning/afternoon with the sun out (not cloudy) and I'm not in a very thick area, I sit tight -- the sun at those times of day casts very long shadows and you're bound to get seen moving around; otherwise, if nothing is going on where I am, I'll quietly pack up and still hunt to another location.
I always carry a pair of hand-held limb shears with me and can build myself a new ground blind in a few minutes if I find another suitable spot (it's best to always have this places pre-scouted). I still have other old ground blinds scattered all around for different wind directions, morning/afternoon hunts, etc.
Lately, I've been carrying a roll of camo netting (the military style stuff) that's something like 4-feet x 9-feet (rolls up small and easily attaches to my pack via a MOLLE strap and a small bungie cord). This thing is great for setting up a quick ground blind, using it for either front or back cover.