I always stretch first thing when I get to the gym, then I do cardio for 10-20 minutes. Then I lift, depending on the day it may be Back and Bis, Chest and Tris, Legs and Core, etc. 1 warmup set of 5 reps, 3 sets at 5 reps heavy weight. I typically switch up the exercises every week, for example, one week ill do bench and dumbbell bench. The following week I'd do dumbbell flys and incline bench, the following week I might max out and also do decline bench. It's all about shocking your body and avoiding a plateau.