Joe
Rattle-cans are no big mystery. I've been using them for yonks now and some folk say that my finishes look quite reasonable in the right light....
There are a few rules to follow, though. The first thing is not to spray if the temperature is less than about 15°C. Then:
1) Shake the can for 2 minutes before spraying and shake it again every 30 seconds or so while spraying:
2) Hold the can between 8"-12" from the model:
3) Move the spray cone along the model in one smooth movement, starting the spray just before you hit the start of the model and spraying until you've just passed the end:
4) Apply LIGHT, EVEN coats only, resisting the temptation to see what it wil look like fully-covered! Yeah - we've all done that... Allow 15-20 minutes between coats:
5) If you DO get sags or runs then LEAVE THEM TO DRY FULLY. You'll then find that most of the mess was solvent and has evaporated, leaving a relatively low "blob" of pigment which you can rub down. If you attempt to wipe it off while it's wet then you'll make a much worse mess:
6) When you've added as many coats as you need, leave the model to dry for at least 24 hours in a warm place. To check if it's fully set, shove your nose right up against it and have a good sniff. If there's even a trace of the smell of solvent then leave it for another 24 hours.
I always maintain that the worst enemy of spraying is impatience.
I hope this helps.
DaveM