If you are playing as the Russian Army, try to destroy the Anti-Aircraft units as quickly as possible, before the enemy can take up defensive positions. Send two groups to each location as soon as possible. The unit near the house is arguably the more important of the two, as it is easier for the enemy to defend with capable Snipers and a minimal ground force.
If you are playing as the Terrorists, take up defensive positions to protect those Anti-Aircraft units as quickly as possible!
Recon can be very helpful in locating the VIP.
If you are playing as the Russian Army, one tactic you might try is to run down the mineshaft near the Anti-Aircraft unit closest to the train cars. This shaft leads to an opening to the enemy base, and while you can't access the base from this point, you can throw grenades, gas, or smoke up into the area, causing confusion and damage. Beware, though, because the enemy can quickly respond if they suspect you occupy the shaft.