just gotta do what feels right to you IMO. When you start tryna fit to certain method i think you constrain ya self. My Philosophy: find a dope sample or song, loop up some bars, chop those up(on the kiks and snares as said before or where they would fall),rearrange those into a couple different 2 or 4 bar loops for a main section/hook section/breakdown/intro outro as for whatever you see fit. Thats the easy part to me. Its all the other stuff that goes along wit makin a beat that can be make it or break it.