As one of the Line monkeys who last year was there when the line formed weds night, and was there for when It wrapped around the building. WEAR SUNSCREEN, and as has been said many times before, Lots of water. And as for holding your place in line, Make friends with the people in front of and behind you. Its a pretty good way to hold your place.
And on another note, Check the weather... As it did last year it could rain, and ruin your day, so please bring appropriate clothing.