Bench Press, Correctly Options

[Castaway]

I haven't thought of my form that much until someone approached my friend and I in the gym. He told us that we should be bringing the weight down so that your arm forms a 90 degree angle. (We were on a flat bench)

I listened to his advice and ended up increasing my max by 10lbs.

Is that the correct way to bench? Is it different for incline and decline?

Note: My goal is to build a bigger chest.