Building a relationship with a VC or angel is just like building a relationship with anyone else. It needs to be fostered and it takes time. Above all, time to build trust and respect, and time to build a sense of how each of you approach problem solving, and how you work together when problem solving. Along with these things you get to figure out if you actually like the guy or girl enough to be a passenger on your startup rollercoaster. I pulled this simple yet helpful list from a PandoDaily post written earlier this year by John Lilly.
John Lilly is a partner at Greylock Partners. Prior to Greylock, John was CEO of Mozilla, makers of Firefox.