Let’s say you’re a beginner riding a great big board. One question you might have is, how do you turn that sucker? Good question! And one that was answered a while back on the Zone, by John Ashley from www.paddlesurf.net; to wit:
Here’s some basic advice.
1. These boards are big- they turn best from the tail so you’ll need to get used to moving your feet on the board especially on an 11’6". Do yourself a favor and learn to cross step- this is the only acceptable way to walk a longboard- shuffling is bad form and is basically a sin. Don’t shuffle. That being said, when you want to turn take a step back – the board will turn much faster from the tail. 
2. Use your paddle! Dip the paddle or drag it- the blade will act as a pivot point and will slow that side of the board pulling you around. Check out all those snazzy snap turns guys are doing where they plant the paddle on the wave side and then snap away from it- it’s a powerful tool- use it!
3. Use your legs. Most guys just try to lean the board over- the board will turn this way but if you really want to get some drive out of the board and some projection down the line out of the turn (and believe me… you do- because this is how you generate speed) you need to get your ass low before the turn, bend your knees, drive the board through the turn and spring out of it. This compression followed by unweighting gets the fin and rail working together the result is a turn that’s more than just a redirection- it’s a torquing setup for what comes next- the blistering top turn! But that’s another story…
4. Look where you want the board to go. Look down the line where you want to be, it all starts with the head. Watch any really good surfer- Joel Parkinson is a good one- watch them wrap full round house cutbacks- slow mo the video and watch the mechanics of the turn- they always look where they’re going not where they’ve been- hips follow shoulders, shoulders follow head. Once you get that down go find some Terry Fitzgerald footage and forget everything I just told you (form, function, style).
5. Don’t fight it- the beauty of bigger boards like yours is the inertia they’ve got- that slow, sure steady, thick feeling translates into a clean line- pure in it’s simplicity- hard for the casual observer to understand how cool it is to fit all that board and curve into a wave and let it run. Go watch Joel Tudor- clean lines, clean surfing, big boards.
Good Luck- if all that fails go have a board made for you that’s a bit smaller and matches the conditions you’re surfing.