Generally speaking, air in at the bottom out at the top, ensureing all cables etc are'nt restricting air flow, a lot depends on your case, mine is really bad for air flow, the psu is immediatly above the cpu, but thers space for 2 fans ABOVE that, not much use as the cpu wires are right in the way!, just ensure air can flow right through and over components where possible.
Next time you wave - use all your fingers