Loads and loads of Vegemite … eaten not smeared in the weeks preceding the trip (or any other brewers yeast source really). It needs to be literally oozing out of your pores. Vitamin E supplements are also supposed to help.
Asides from that the only thing I’ve found that works is good old Deet. Spent 8 weeks working at the Inti Wara Yassi refuge in the Bolivian bush and believe me … tried EVERYTHING.
Also remember the more dangerous buggars (i.e. malaria’s) come out mainly at dusk / evening so thats when you need to be covered and doused up. Burning the mozzie spirals will also help lessen the population, but make sure you don’t burn the place down.
Also avoid wearing perfumed products as much as possible, that can attract the little beggars (along with breathing … but harder to cut down on that)