Free spool pay out of the cable saves the battery as said, also much faster. Keep your winch spool lubed, just a few drops of oil at ends of the spool each year at annual maint., Keep engine revs up while using the winch multiple times so to keep your battery charging to the max available. Installing a winch battery is a smart move, but it too gets tired after multiple runs. Might want to occasionally run a oily rag over the extended cable to keep it from rusting and binding on the spool. Never pull the cable fully out, always keep two or three wraps on the spool before putting the winch to work. Watch those cables/ropes they do break once in a while.
Yup, get a tree strap, snatch block and a 30' strap/rope/cable to extend your 50' spool cable reach, the tree you need to pull from is not always within 45' of your winch spool, ask me how i know. These also help when pulling a friend out of trouble. Check Harbor Freight for basic emergency supplies.
Warn Corp. has videos and lots of great advice on winch usage.