you should get into the habit of using preworkouts only when you need them, not every workout. once tolerance builds up and caffeine addiction kicks in, lif starts to suck. then youll have a month or two of dull workouts
and the words "proven" and "supplements" hate each other. google any supplement, and youll fund contradicting evidence for it. in the end, youll have to find out what works for you. an example for me is yohimbe. some people love it, i personally hate the ****, makes me feel like im dying.
look into craze. its a preworkout that revolves more around focus than energy or pumps. its my favorite along with many others. just dont let the tolerance build up. it sux ass once that happens