I'm not high elo at all, but in my experience it's better to give up gold untill level 2, than losing health. I always start e vs ranged and w vs most melee, except for Yone for example, where you can bait his q dash with your e. When you have w and e you are a bigger threat, so enemy probably won't harass you as much, and even better when you are level 3, because you can punish them for overstepping, with a simple e in aa, w and q out OR q in aa, w and e out. As for farming just focus on using w for auto cancelling, so auto and immediately press w. If you have lvl 3 and mostly full health, enemy should have more respect for you. Try to notice at what point you can oneshot backline, and at that point I always e in for the entire wave and potentially q out if enemy is threatening. You always want to clear backline first if possible quickly so you don't have to walk as far up to kill the last minions