To answer the question posed by the OP in the thread title I have to confess - not very!
I'm in awe of the Bomber Command (and Luftwaffe) guys who managed to find their targets, particularly before the Pathfinder Force came into being. Sitting in a nice steady Hastings with the benefit of H2S and with no night fighters or flak to worry about I still managed to achieve a nine mile error (bombed the wrong reservoir dam in Yorkshire).
Still, it secured my posting to tankers and saved me from years of sitting in the black hole down the back of a tin triangle!