Try searching t'internet for the "rustoleum method".
It basically involves using foam rollers and the rustoleum paint,then 800 cutting each layer and buffing to a good finish.
Worth a look,some of the jobs on there looked mint.
If you rattle can it in this weather it'll just "bloom" ie look like there's a white tint on it.
Also,if your using rattle cans put them in very hot water first and buy one of those plastic things that makes it like a spray gun,only about a fiver.
I've had some great results over the years with rattle cans and cutting back but often it's cheaper to just get the paint wholesale and just do a rough spraygun job.