I mix bicarbonate of soda with that amino acid, some table salt, plain liquid, and occasionally a stimulant. I prefer minimal ingredients overall. I raise the bicarbonate level bit by bit or else I end up with loose bowels.
My usual habit has been to grab a quick energy boost then add creatine once the session wraps up. Reading around a bit shows some support for mixing in a product that has l-citrulline and beta alanine together with the caffeine so I could squeeze out extra work during training. Blends sometimes put the creatine in as well and comments also point to l-theanine or ALCAR as things that might add value. Checking into any of this quickly leads to promotions filling every screen. A handful of products from different makers look worth checking out. Curious what others actually use or skip entirely especially when the focus stays on heavy sessions.