Most drummers/bands use 4/4 time, so usually you can count along really perty easy
. Then there'll be groups that fell liek throwin in rand time sigs. Best thing Ic an say is find the pulse of somethin and count with it. Usually you can count 6/8 in 3's(1,2,3). Least in the band music at school we're usually able to, just makes stuff easier sometimes. Jazz is one typa music that lieks to use different sigs decently often. Metal too, but not as much till' you start listening to near anything with derek roddy on drums :P