Use the AWP! j/k, lots of good advice here, however, I would try sewers if I were you. It is run and gun CSS style and most of your enemies are straight on. Remember that the nades are not nerfed like in CSS and they can be primed, also if you hold them too long ... well I am sure you know already. BTW, death nades (killing enemy with your primed nade after you have died) are the best
I use it to go to pistol quickly when necessary. It will save your life. Waaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaay faster than a reload. Others will not do this, and you can bang bang bang them with your little pistol.