lazy hop-up tactics for me, increase the amount of hop until it starts curving upwards, then decrease slightly until it seems to stop.
for zeroing a sight, i have a b&d work bench, so take that into the garden, put a towel over it and clamp the gun in place, ensuring it's totally upright and not leaning. Then setup a target and fire a load of shots at it. I'll then try and adjust the left/right on the scope so it's pointing in the middle of the cluster. If the vertical axis is massively off i'll usually try set it so its abit higher than where i've hit on the target as my garden is about half the length you'd consider using a scope to hit someone at, but most the time i don't bother.
For my air-rifle i'd repeat this process a few times to get it perfect, for airsoft, they aint accurate enough to merit too much trouble