Vitamins

I currently take a mutli-vitamin (almost everyday, sometimes I forget). What other vitamins help in addition to a muti-vitamin? Should I be taking more vitamins of any kind? I don't really know a whole lot about the subject and when I go into places to ask I feel like they are just trying to sell me stuff.. I do not want to take and diet pills such as 1DB goddess or hydrycut or anything like that.