What should I keep when I begin harvesting?

Gonna harvest this weekend, I would like to keep the extras to make hash or oil. Are the big fan leafs worth keeping? not sure if they would have any thc on them and obviously keep the leafs cut from the buds. Would probably wait till i have a large amount of extra clippings to make it worth the effort. Just wondering whats worth keeping. I take it the best way to store it would be dried like the buds then kept in the freezer.

Thanx

I dry my leaves roll them up and smoke them in place of cigs.....very smooth....great taste