5 steps to a fast multiplayer game level design.

Do you want fun, fast multiplayer gameplay in your Counter-strike Source level? Here are the essentials to achieving this type of gameplay.
1.10 second rule. It should take no more than 10 seconds for a player to run from their spawn to the center choke point of the map. Any longer and the map is probably too large and the map is no longer a fast style gameplay. It then becomes a map with slightly slower gameplay because players have a harder time finding each other to kill. When you create your map, time yourself running from the spawn points of either team to the spawn point of the center of the map where you envision most of the conflicts happening.
2. One is lonely, two is nice but three is genius. Typically giving a player three ways to enter a choke point area, the place it takes 10 seconds to reach, is best because that way it doesn't spread out the map over too large of an area and it's going to make the opposing team have to watch three points of entry which is always harder than watching two.
3.Game path economics. Giving the player three options of paths to take should involve trade offs. There should be one path that is almost a direct path into the choke point area but it has almost no advantage to taking it other than it gets you there first. The second path should have some sort of tactical advantage to it but it might take a second longer to reach the center but the tactical advantage should make up for that. Then I typically like to make the third be an odd vent or ceiling drop in that the teams can use against each other but typically it takes the longest time to get to these locations because of the high tactical advantage they present.
4.Crouching is a single player feature. Never make a player in a fast multiplayer map crouch. As soon as you force that on the player, your map play slows down because crouching often times places the player at a disadvantage and they can't move as fast which really slows the map down for gameplay.
5.It's so sunny outside. HDR is great because now level developers are encouraged to build outdoor maps because they can use those very cool HDR effects. Fast maps need to be lit well because if a player goes into a location that they can't see well, they'll start moving slower in order to be more cautious.