hungup, are you thinning out your paints w/ water? Its much easier to get things to lie down smooth and w/o stripes if the paint is thinner.
I thinned my paint out quite a bit, then pretty much went nuts while painting -- left/right (let dry), up/down(let dry), diagonal(let dry), other diagonal -- then I started making random swirling motions w/ my sprayer -- thinking the eye has a much tougher time picking up random. :)
But each of my coats was pretty darn thin. For me, when the paint got too thick, I start having a tough time w/ hot spots and sparkling -- and I was too lazy to do a top layer to tone it down. :)