On guylines to stake out tarp: Bowline to tie line to tarp. Clove hitch to add shockcord tensioners to line. And taut-line hitch at the end to adjust length of line and to make a stake out loop. All of these are very easy knots and once you tie them, most don't have to be retied. All knots should be inspected though while you're using them.
Before I started using that hitchcraft thingy, I used a slip bowline to tie the tarp to the tree strap. The thingy thing is just soooo much easier to adjust.