In the A8, drain off all the AUX tank first (maybe even before the drop tank, although I typically don't). After that, drain the Aft tank down to 25%, at that point you are as manueverable as you are going to get in the A8. From there use the FWD tank, head for home when the FWD tank is about 25%. Well, if you are farther than half a sector from home head home when the FWD tank is at 25%, closer than that you can drain it dry and head home on the aft tank, you'll land on fumes.