What Marc G said about soaking the rattlecan paint in warm water before spraying. What you want to achieve by doing this is to get the contents of the can up to the recommended optimum spraying temperature.
BTW, giving credit where due, I first read about this technique in one of Micromeister's technical papers. Not sure if he's the inventor of the technique, but I learned of it from his work.
As to Krylon vs Rustoleum, it's now kind of a moot point. The original Krylon paint that rocketeers swoon over is no longer available through normal retail outlets. You can purchase it via industrial channels.
I find Rustoleum lacquers although available only in red, white, black, and clear work well for the base coats.
The Rustoleum enamels are nice, too. You must however be careful with Rustoleum enamels "spitting" at random times. Wipe the nozzle frequently, shake the can frequently, and keep your fingers crossed. A rabbit's foot might help as well. You still might get a spitwad in spite of these precautions.
Personally, I like the Rustoeum fluorescent colors as they are easy to spot in the sky and on the ground. I spray a white basecoat over white primer and follow up with two color coats. Without any sanding whatsoever, I follow up with a two coats of Rustoleum Crystal Clear Enamel for a smooth glossy finish that is both BRIGHT and strong. The down side of this paint treatment is the added weight but then again, I build tube fin models (high drag) so the weight doesn't bother me at all. Just makes for lower altitudes and shorter recovery hikes. I'm old and would rather launch than trek cross country.
Kit (AKA Cranky Kong)
Total Total Impulse as BAR: 7,753.69 Ns (Equivalent to a 51% M motor.)
On any number of government watch lists...