One Shot One Kill

Jade's catalyst missile costs 90 tiberium to deploy and if you are quick enough can be avoided if the unit has a decent speed. It is much more catastrophic when it hits a tib field or tib gas from a chem trooper/buggy but one tell that I've learned is that if their chem trooper begins to run away, you probably have a missile inbound, so it's time to get those units moving.

If you want to have a catalyst missile explosion in your pocket as GDI, consider solomon who has a much more powerful attack that does 1 tile AOE (at reduced damage) around the area if impact. The target tile is a death sentence and the surrounding tiles will be wiped clean of infantry and light vehicles.

understanding what commander you are up against is very important for how you play your match.

If you are facing jade/solomon/kane who all have very expensive powers, consider keeping their harvester under constant harassment so they can't build up that bank.