Cable Cross-Over
While a cross-over might sound easy enough, the progressive weight increase on every set is not. The first set of 20 reps is all about priming your muscles for what's to come.
"Get your muscles, tendons, ligaments warmed up with that first set,"
Pause and squeeze at the top of every contraction. This will make sure your chest is working as hard as it can. keep a slight bend in your elbow, and make sure to stretch all the way back.