Whenever I have taken a supplement...I don't take as directed (as in several times a day). I just take them once about 30 min before I'm about to work out for some extra energy. That always worked for me...instead of taking them am, mid day, etc as some of them direct. I find no bad side effects and it's cheaper
I bought a bottle of just straight up caffeine pills from bodybuilding.com for like $5 (100 pills). I don't like coffee, but I know a lot of ol' school gym rats that swear by drinking a cup of black coffee before they work out for the caffeine. I take one pill before I work out instead and I'm good...they work better for me than the $50 bottle stuff! Most those supplements have caffeine in them anyway(that's why a lot of people get jittery or if taken too late in the day can't sleep).
The down fall about supplements is the FDA doesn't look over any of that...meaning they can print whatever they want on the label and no one really holds them to it. I agree with Coy though, I know several people who have taken HC or Lipo-6 and really liked it. But everyone is different...and if you have high bld pressure, kidney, liver or heart problems I wouldn't take anything. If you don't need a supplement, save your money and go all natural. Less for the kidneys and liver to process!
Best of luck!