We really should have a guide about basic upgrades.
The logical way to make upgrades is to start with the compression part of the airsoft. Those are cylinder/ cylinder head/ piston head / nozzle / bucking. You are looking for a good fit of those pieces together to have an airseal as good as possible. A well tuned airsoft will have a deviation +-2 FPS. Some even report less deviation but +-2 is a good thing to aim for. With consistent shots and less airleaks everything will work better.
Lucky for you, those parts are not very expensive. And some of those in your airsoft might already be good enough, you'll have to test them.