I use the circles too... as Luds was saying, I go up through the bottom jaw and out behind the eye... try and get some skull
this make for a much stronger hook-hold.
Rockport--- I bet the eels you were using were small is that correct? Those little pin-snakes as I call them, are acrobatic little bastids, it seems to me that because they are lighter and wirier (that a word and a half
) they can still get their tail up around the hook, even on the retrieve, and pop the hook right out. You may want to smack their tails on a rock a few times to take some of the fight out of them. I've had that happen many times... and always with small eels (9" or shorter).
Hope that helps,
-Dave