I like to get somewhere where birds frequent and where I can hear well. I will make one series of yelps on my way to the spot, then one when I sit down. Then silence for an hour or so, hopefully one will fire off on his own, but many times I end up slipping around and calling.
Best advice I can give, is don't hunt too late, sure you can kill them late, but you can also really screw up your chances for the rest of the season by hunting them late in the afternoons. I won't hunt past about 5 est.