Hey dude,
Fin position, right back for hold on the nose and further forward for turning.
Longboarding and the trip to the nose is all about going with the wave and finding correct trim and positioning... But dont take it from me, I'm pretty crap

learn from the experts...
I'd google:
Tom Wegener nose riding, I've posted it here before and its a great detailed article.
Cyrus Sutton epic TV, has a great 4 vid "how to" cross step, nose ride, trim etc
Wingnuts Art of Longboarding, the whole vid is on YouTube, it's real kooky but the info is great, he goes into basics of stuff, turning, getting out, catching waves etc which is great bcs your practiced short board techniques here are all different once you add 4" of board.
Check out the "More Longboarding" thread, it's the best thing on this forum and a brilliant collection of classic vids.
Enjoy