BC Rider sums it up, there ain't much science to it.
IME I find the biggest factor (other than preventing any air gaps) is the boolit lube with BP cartridges (use lead the softer the better but I've only got hard cast right now, they work fine), now everyone has their special recipe but the best one I've found (no criticism here of anyone else's recipe) is dead simple (and dirt cheap) 50/50 Wal-Mart olive oil & pure beeswax. Melt together with a double-boiler style setup on your stove and pan lube, call it a day...the other day it was 30 degrees out and I managed 50 rounds through my .45 Colt Uberti, without any stoppages and still hitting the steel. I find it works just as well in the cold (we usually don't get below -15 here and I usually ain't shooting below -5 but still). I'm also not shooting groups just plates and poppers, so minute of "Down Zero" is good enough.
Oh and keep the lube and yer lubed boolits secure from mice...don't ask me how I learned that...