You’re good with a daily multivitamin. Otherwise, just eat a balanced diet, without overdoing the protein and without skipping the carbs. You need carbs to train with any intensity. You need to do cardio if you want to get shredded, and you need carbs to do effective cardio.
I used to cycle creatine, it does give you another rep or two before failure, and it does juice your arms up. It also made my face puffy which wasn’t a side effect I was willing to deal with, so I stopped taking it.
My aunt is a doctor and said both protein and creatine supplementation is extremely taxing on the kidneys, so I stopped supplementing for gains. I do take a collagen supplement for my skin, and a daily multi. That’s it. I’m happy with my musculature.
I’ve read that beet juice and baking soda can both boost performance. I haven’t tried it myself, so I can’t confirm.