No you're right, you posted nep. I don't see the problem here.>>160395443
90% of good last hitting is focusing on what minions are attacking what and controlling the wave. Look at the damage each minion does, how fast they attack, and which minions they can target.
For turrets its the same deal, look at how much of their bar is taken with each hit and auto accordingly.
For most champs in the early game, a melee creep will tank two tower shots alone and be one hit away.
For ranged creeps its the opposite, one tower shot, but two hits away to kill, so auto once beforehand if there's no minions to deal that sliver of damage.
Also for cannon minions just repeat what I said about normal minions, and if you need to cast a spell do it right when its one shot away from death or just auto it.