Source: http://www.playinsurgency.com/forums/topic/571-tips-for-starting-with-insurgency/

Tip 1: Seek High Areas / Staircases

From high areas, you can overwatch the situation. In Siege, there is a staircase at the beginning of the Security spawn. You can use this to enter a higher area which has a perfect overwatch on point B. Provide this overwatch to your teammates and capturing B will be basically peanuts.

When executing this tip, you might want to look out for snipers lurking around.

Tip 2: Aim for the chest

In Insurgency, I experience it best to shoot at the chest. Shooting in the head might be more effective, but is a lot harder and the efficiency lost in shooting on the chest isn't a lot. Two or three bullets to the chest will usually do the job with the M14. Take advantage of the fact that Insurgency takes weapon realism and lethality serious, and that a player isn't basically invincible when they shoot at the chest!

Tip 3: Help each other

It is always important in games like these to help each other. Best way to do that is to keep microphone contact with each other. When approaching a capzone, you might want to call for cover if you don't already have it.

Tip 4: Take inroute building routes

When approaching the capzone, you can get snapped by snipers lurking around the street. Best is to take the inroute building routes. Doing this will prevent sniper usage against you. Always keep your gun prepared when doing this though, because you can always come across CQB's in building routes. If this happens, you want to quickly squeeze the trigger.

Tip 5: Don't lone-wolf [IMS: unless you really know what you are doing]

Always try to get into a team. Walking alone in Insurgency, and you're basically a dead man walking. This tip is basically directly linked to 'Tip 3'.

IMSID968F27FDC1D5FDC46E82F5C5E51734D098A96F1B