I personally dont believe in the protein shakes and supplements. I think their positive effects are mostly stimulated by mental coercion. Imo, the best, most easily digested sources of gains in muscle mass are from natural meats and vegetables high in protein, in conjunction with lots of rest. Oftentimes, protein powders can do more harm than good.
Caffeine is a great drug for lifters, but most preworkouts deliver a caffeine dose way too powerful for regular use. Imo moderation with caffeine or any other similar upper is key with preworkout supplements.
Don't ever juice. Youre only lying to yourself. If you have to ask whether or not you're juicing, you already know.
Last but not least, if youre serious about performance in lifting and/or building, abstinence from alcohol and nicotine is a must. As well as any other substance that interferes with your natural biorhythm. Im not religious or straight edge or anything like that, i can just tell you that, from experience, reliances on these substances will always hinder your abilities in the long run.
Thats my whole spiel on supplements and the gym/gains culture obsessed with them. Not that anyone asked. Don't ever take supplements cause someone said you need them. The power is in you, not some chalky powder.