Many lifters learn the bench press from powerlifters. And powerlifters certainly know a lot about it. But remember, their goal is to lift the most weight possible for one rep, and they often use special lifting shirts.
If your goal is to build size as well as strength, and you lift raw (without a stretchy lifting shirt), then your pressing form will be different. Here's a quick video lesson.
We posed the following question to 7 coaches: "What one thing has made the biggest difference in your training when it comes to putting on muscle?" The answers varied enormously, but one of them might provide the clue you've been waiting for.