Watch frag movies, your subconscious will automatically learn where the "pros", the players in the video, is. You will learn the spots, and use them without knowing.
Try to remember yourself where the spots are, and what kind of tactic-setup they are using, if they are aggressive or defensive, semi(be aggressive and then fall back). Try to use all kinds of tactic-setups when playing, know your enemy, if they are aggressive, be defensive, if they are defensive, be semi.
However if they are semi, you have to got be dynamic, meaning you will change your tactic-setup for each round, making them confused.
Even a person like me, playing on the mid-high level, is still watching some frag movies.
I like to use ether http://vault.alienwarearena.com/ or http://www.source-movies.com/
and about the Source Demos.
You can use the source demos for both watching tactics for you team, if you are team-leader, or as described above, learn spots, and tactic-setups.
Thats all for today.