New to breeding, and I'm actually having the most problem with the easiest part of the process:

Which IV am I aiming to NOT inherit? Which Nature it best?

I really don't want to look these up every single time I try to breed something. Sure there's an easier way, even for someone that doesn't know all this stuff offhand.

I do know that for IVs, I'm looking to skip either ATK or SP.ATK, depending on whether the pokemon is physical or special.

Do natures follow the same rule? Should I get a +Atk/-Sp.A nature for a physical 'mon and vise-versa? Anything that needs to go slow is obviously +?/-Spd, but what about defensive 'mons/walls? Sure it seems obvious that I need +Def or +Sp.Def, but what can I afford to have reduced?

Help I don't know what I'm doing.