Counting the cranks is a good way to avoid spilling too much. Let's say that on an empty tank it takes 100 cranks. Then you know that when you hit 95 or so, you'll want to slow down. You could stop at 95, bit I like to be sure the pump is still working (you know how those things can slowly go bad)

Then after each flight, count again. You'll usually find that you use about the same amount of fuel each time. So maybe, after each flight, you'll need to slow down at around 50 cranks.

Yea, you'll still spill a little, but as long as you're going slow, it won't come out too fast.