if it rolls, turns, pivots, or has threads on it, grease it. lube the chain. I spray , then wipe chain and derailleur pulleys weekly with WD40. Cheap and readily available. But, really, grease and properly adjust your wheel bearings, if they take grease. You will see a difference.

Oh yeah, buy a tub of bearing grease.

edit: Check yer brake pads, cables, shifter cables, etc., with an eye to reducing unwanted friction. A little brake rub is meaningless up to a point, maybe, but it'll make you tired.

After that, grease some more stuff.