When your doing Siege online, hopefully the timer is on 15 minutes. If it isn't then too bad.

Anyway choose to be NOD. Then build lots of refineries and power plants.

Now build like 4 air fields. Make a tech centre and upgrade the venoms so they shoot lasers.

Make like 40 venoms in each airfield and max amount of bombers 1st! Then you're done!

Use all your venoms to attack. They are quite useful for scin air craft because they are fast to build so they can attack in like 50's!

Even if mammoths are used make them attack them 1 at a time. Same with other enemies.

Don't forget about getting some scorpions... a bunch of them too. They would be useful if the venoms were dealing with the aircraft. The scorpions could help with the ground vehicles.