Sometimes if the veins are fragile, I have found that they blow if you use a tourniquet...if the first one blows, and you can do it without using the tourniquet, try that. But of course, if you can't see/feel the vein without it, you shouldn't try to stick them because going in totally blind is NOT a good idea! But I've found that this usually works on the little old ladies where you can see their veins from a mile away...sometimes the pressure from the tourniquet is just too much for them, and as soon as you pop into the vein, it's over.
It's 2 sticks for us, too. But I'm lucky - I work with nurses who have been working with cancer pts for 20+ years - a lot of them could get an IV in a tree branch...so if I can't get it, I just find one of them.