Benchers will try the fanciest techniques in order to bench press more. One technique that thousands of benchers use is called the "reverse grip bench press". Why do benchers use this technique? Well, they can bring the weight down to their lower stomachs, and as a result they don't have to press the weight as far. Anthony Clark was one of the best benchers from the mid to late 90s and he was using this technique. He was in fact benching more with a reverse grip than he or any other bencher could bench with a regular conventional grip. Many lifters started to follow Anthony's trend and as they started to use the reverse grip bench, a lot of bench pressers were getting hurt. Lifters were in fact getting hurt so frequently, that all the powerlifting organizations banned the reverse grip from competition.
I don't recommend using a reverse grip. For one it will take a long time to actually be successful at it. Secondly it's illegal and finally you will get injured before you even have a chance to get very strong. So the bottom line is save your destiny from being injured and bench with a conventional grip.
Another grip to avoid is the false grip bench press. This is the grip with your thumbs out. You should avoid this grip for one, you can't bench nearly as much with a false grip compared to a regular grip bench press because the fast twitch fibers, forearms and triceps aren't being as activated. Secondly, you are more likely to lose control of the bar and get hurt. In fact many injuries have occurred just because lifters weren't using the proper training grips. There have been lots of broken ribs, internal injuries because the bar will start rolling in your hands during the ascent. Nothing can stop it and it will crush you.
So what's the solution? The solution is to bench with a regular grip, and by gripping the weight as tightly as you can every time. By doing so will diminish your chances of injury, make all your benches legit and you will become a lot stronger in the long run.