Last hitting & Gear adaptation

I've recently started playing against other players, and am having trouble last hitting creeps early/mid game. Some games, I can do just fine and last hit at least 70-90% of them, and other games my CS is just pitiful. I main and find that his E puts in a lot of work mid/late game, however early game is where I lack the consistency. I understand that practice makes perfect, however, there are certain things that might prevent me from getting a good CS due to the amount of pressure the opposing laner puts on Malz, especially with his dependency on mana.

I can consistently CS early game with my secondary main, , because his Q is amazing. I actually do really well with him(for my level). I don't main him because his Ult doesn't do as much damage to non AP champions that I've faced.

Another issue I have is adapting my gear to the opposing team's builds. I've attempted to do so, and still get obliterated even when not in a team fight. Any tips you guys could give me is greatly appreciated. Thanks. :3

My best PVP score with is 6/1/10(16/0/6 in bots) and with it's 10/4/9(19/2/5 in bots).