GTA3 making sure you don't screw up

How to prevent locking yourself out of 100% in GTA3:

-- Make sure you do everything in Portland before you do Salvatore's "Last Requests".
	-- Main one to worry about here are Luigi's and Joey's missions, but I'd strongly recommend doing vigilante/paramedic asap,
		together with the phone booth missions.
	-- Turismo is a repeatable phone booth mission once you've done all of 'em! No need to re-do it.
-- Make sure you do Asuka's "Two-faced Tanner" and all of Kenji's missions before doing stuff for Donald Love (which is way further into the game)