All things being equal... on a body of water that has big fish, you've done your research etc. I'd say the first big fish is luck and any subsequent large fish start leaning toward the skill side of things.
As far as tilting the odds in my favor... timing is the first thing that comes to mind. Rinse and repeat. If I caught big fish on X under Y conditions at Z time of year I will for sure be trying that again. Fish when the fish are more maybe a little less wary pre spawn, post spawn fall feedbag, stained water. Fish when others don't, nighttime, less than ideal weather (while being safe), etc.