Myself, basically, I just play behind the big yellow box. I vary my actions from peeking behind the box, doing wallbangs (if I feel that there would be many Ts in middle), and throwing SG/HE to the radio room either at the beginning/middle of the round when the Ts like to press that place.
I also always tell my teammate to stay behind the wall which is under the CT ladder to back me up by being stand-by there holding FBs and to throw them to the radio room hallway when I say the Ts are rushing, or whenever I want him to.
Sometimes when I'm running out of nades in the middle of the round, I just position myself in a position which allows me to pick at least easy 2 kills, or hide at the lower bombsite when the time left is around 30, and tell my teammate to stay at tower because I leave the ramp loose.
At other chances, we also try to steal 1-2 kills by pressing the radio room and hut, whenever we notice that the Ts tend to vary their gameplay between slow safe round, and fast offensive round.
I play CS:GO. I go there with my gun 1 spot, ofc when u cant wallbang I can just wait and they have to come from exactly there without any way of killing me before it.. Then I just press mouse1 down and get 5man multikill like I alwways do in CODMW3 also
at the beggining throw smoke and flesh to stop tt rush then spray kill -4 change to USP kill 5th win round buy AWP make double head kill make 1.5 kill ( the second guy injured to 50 hp throw he kill other tts couse my teammate will wallbanging all the time with cow :)