If you are showing no particular deficiency signs and your diet is balanced and healthy then you probably don't need to take any. You need to be careful not to 'overdose' on some vitamins (i.e. get them from your diet and then more from a supplement) as they can cause damage to internal organs.
Best advice - check your general eating habits to increase natural sources of vitamins and remove items that can deplete them.
A supplement that has made a big difference in my life and of a few friends I shared this with is vitamin B-12, 1000mg. I was waking up feeling tired and sluggish for a long time. I felt a huge difference in my energy level after only 3 days of taking the B-12! It is needed to turn food into energy. It was a wonderful, cheap fix for me!