How to improve macros?

As a jungler I wanna improve my macros as i think its the most important thing. I was iron, focused on 1-2 champs and my clears (around 3:04 with nocturne) and tried to not ult mindlessly and play for picks and around my team’s wincon. That helped me climb to b4-b3. I understand that its still pretty low elo and ofc there are many things I have to improve especially my macros. So what’s the best tip to keep in mind? Is there a specific guide or checklist that should be in my head while playing? I generally always try to check other lanes while im farming my camps but I dont think my decisions are always the best! Any help would be appreciated.
My riot id (for opgg) is: YPATOS ARMOSTHS#cfa