What's the best way to transfer from Long Beach airport to LAX?

well from Long beach airport you could take the 111 Long beach transit bus to the Transit Center. (pay 90+40cents for a inter-agency transfer) then you have a choice you could board

Metro 232 to the Lax city bus center then the Lot C bus into lax

(mind you this route takes about a hour and 1/2

you could opt for going to transit center then boarding the Blue Line take that to Green Line, then take the green line (your inter-agency transfer) will be valid on the rail lines)

to the Aviation station then the free Lax shuttle into the terminals

When it comes to airport stuff "Kingsley" is the expert. The easiest way to travel from the Long Beach airport (LGB) to Los Angeles International (LAX) is by shuttle van (Super Shuttle or Primetime) It is about $25.00 for a shared van to $89.00 for a chauffeured limo. It can be done using public transportation if you have several hours to waste, and don't mind lugging your travel cases on and off several buses and trains.

cruise the 405 to the 710 N. Then take the 105 W. Voila

Call Super Shuttle or Primetime Shuttle

On a plane or helicopter--duh!