Once you get to the front of the Convention center, look for a person in a volunteer shirt or vest and just ask them where the badge pick up line is. They will show you a massive line somewhere... you just get to the end of it and shuffle along with the masses.
Anime Los Angeles 2011-2013, 2015
Anime Expo 2006-2011
Wondercon - 2013
San Diego Comic Con 1994-present
Comikaze Expo 2011, 2013-present
Long Beach Comic Con 2009-2012
Anime Conji 2010-present