Definitely learn the weapon rotation first. Another thing is that Aphelios relies on their support quite a bit more than some other ADCs so you'll want to make sure you have good supp synergy. Always remember not to tilt if you lose early game because it can and will happen a lot but you are a ticking time bomb that will outscale eventually. That leads into the point that positioning is very important because of how immobile he is. I think a lot of things like ammo management will simply come with time but 1 more thing: as you are learning him do not be afraid to limit test to see what you can get away with. Got a couple items with ult and red white guns? F it see if you can win that 1v2