This isn’t really an easy question to answer, because without knowing how you are losing or why, it’s hard to give you the best advice to help you win.

The key with the latest C&C games is sadly less about strategy and more about rapid prioritizing. GDI is the most powerful faction, like it or not, especially when they start sending mammoth tanks after you. If you want to turtle up and build up resources and a base, then you have to be able to withstand the waves of forces they send at you.

The best way to do that, is build those powerful laser turrets which are very strong against tanks, the Scrin have a very similar anti vehicle emplacement option, I just can’t think of it’s name, but as many of those as you can get available to you and built in as short amount of time as possible, that’s your best defensive option to survive while you try and build up massive forces to overwhelm their base. If you take this route, going for the mechs or giant scrin walkers is your best bet, a half dozen to ten of those things will demolish pretty much everything in their path, especially if you send in a few cheaper and faster vehicles just ahead of them to draw fire and take the damage at the cost of some units while you let your walkers get in there and start leveling key structures without taking too much advanced damage.

If your looking for a quick strike win, which is probably the easiest victory against GDI, then defend the base as needed until you can build up some bombers, send them in to take out their key buildings like vehicle buildings and technology centers, and that will give you a little more breathing room while you build a larger force to finish the job. Just keep sending in the bombers and hitting targets smartly and you will knock them out quickly.

Sadly the game has just gotten too action heavy these days, and you can’t really go into any match or map thinking about a nice solid strategy, you have to react super quickly, because the way they have the AI working, it builds units immediately and starts sending increasingly difficult waves of enemy units at you without relenting.

So as soon as possible, you have to either build for defense if you want to turtle up, or build enough defense to survive and quickly build for a smart attack to cripple thier advancement. It’s really that simple.

Good luck.