one of your problems is your ping.
if you have a high ping you cant switch fast, if you switch you are to slow ...
try to quickscope ...
i know its at first very difficult ...
but if you learn it, it would be very easy ... and your aiming will be better :P
if you want to lean quciksope fast
1. aim a person
2. push you mouse buttons in the same time ^^
thats the way that i learn it XD ^^
sorry for my bad english :P
maybe i will upload the next time
on my youtube channel a tutorial "how to learn quicksope"
but MAYBE^^