The biggest key is diet. Cliche, I know, but it's true.
When I first started working out, I thought I looked okay. Then I added about 100 grams of protein to my diet (mostly shakes) and took a nitric oxide product, and I gained about 15 lbs in a very short time period. People started making comments about how big I was getting. Keep in mind, 15 lbs for a guy my size makes a big impact.
You need to balance that with good, quality carbs to fuel your muscles and prevent muscle protein breakdown.
and plenty of water!!
Outside of that, if you want to take other supplements, then you probably need to experiment with various ones to determine which ones impact you the most/best. What works for one doesn't necessarily mean it'll work for another. For me, NO products have worked best.