The commonest way is catch a taxi. When exiting Noi Bai International Airport, you will see the taxis lined up against the curb. There isn't really a taxi line as such just pick a cab you like or wait for more to come. There used to be numerous signs giving the fixed price: VND 350,000 ($16) for a sedan and VND 380,000 for a MPV (7 seater, Toyota Innova). However, these have gone, so you can either negotiate a price or pay by the meter. Usually, VND 350,000 is quickly accepted.