1) Engineers who protect base can save up money, buy vehicles, and then store them behind NOD Tiberium Ref. or GDI Weapons Factory ( As long as lamers don't come along and steal them, however most of the time, they don't check ). This way, others who have spent their money on Weapons or other items won't have to wait to buy vehicles. It may not seem like the best tactic, but you'd be suprised how much faster your team can advance this way.

2) Drive Humvees ( Bugies? ) in buildings! For example, when some NOD APCs decide to infiltrate the GDI Guard Tower, you can only guess how funny it would be when they are ready to plant Remote C4s/Timed C4s/Nuclear Strike on the Control Panel and to their suprise they get run over while inside. You can also stay in your humvee and block anyone from coming in, but sometimes people take advantage of this.

3) Use Stealth Soldiers to gain access to GDI via Harvestor. I am not sure if anyone has mentioned this one, because sometimes I see people try to do this. Anyway, you buy a NOD Stealth Soldier, use the GDI Harvestor as a sheild and make it to the back entrance of the GDI Weapons Factory. This one takes a few tries and can't be done in any lag, but I have done it a few times before.

4) Run People over the fun way! I know everyone knows this one but for those who don't, you have to try it. Get a Stealth Tank and carefully go behind GDI Infantry while they are Sniping, AFK or Shooting at other NOD. Then, from there you run them over. However, make sure you don't do it where there are a lot of rocks for the enemy GDI to hide or escape and don't make them see you in anyway.

I forgot a lot of my tactics, but I guess if I remember, I'll post them as replies or something. Have Fun! ^_^