I'm pretty sure I got the info from one of the members here, but I dont know who to credit. We have a horrid POS Master laminator which we cursed on a daily basis until someone gave us these tips.
We release all tension from the rollers and manually adjust so that we "feel" they're equal gentle pressure, raise the top roller up a full turn so the media and lam will slide through. Pull About 50% of the project (give or take) through the rollers and make sure the lam 100% lined up to the media, turn the tension back on and use the motor to retreat the media and lam back out. Watch for any indications of creases or wrinkles over the course of the retreat, if it looks like it's going to get ugly, abort and retry from the 50% through stage. If all is going well, stop the media before it comes all the way back through leaving you a ~3" tail. Fold the liner of the laminate under itself so that you have a ~1.5" piece of lam to lay down on the media. Again, retreat the media so that the 1.5" tip is in the rollers and you can grab the tail of liner out of the project. Size dependent, I usually pull the liner clear and watch the project entering the machine and have someone else catch it on the other side. Lots of times it isn't 100% necessary, but if they're handy I take advantage of the extra help.
I hope it all makes sense...
Using this kinda outline we've never botched a lam job ever since. But our longest is about 12', nothing heroic like.