I played Turok 2, Goldeneye, Perfect Dark and Timesplitters 2 multiplayer modes with friends and family, but I don't remember actually focusing on aiming as much as I was moving at high speeds (moving with the yellow N64 buttons was the best) and unloading my gun on whoever I met with quick reflexes before I quickly moved about again. I knew the ins and outs of every Perfect Dark map after awhile and how to quickly get to people shooting at me from a distance.
It wasn't until I played Team Fortress 2 on PC that I focused more on aiming. It's so much easier with a mouse, plus if you play Sniper from time to time you kinda have to get good at it.