Check the form of calcium in it – if it’s calcium carbonate, don’t take it
Ditto #1 – for magnesium oxide
Look for active forms of vitamin B2 and B6 – these will say Riboflavin 5′-Phosphate and Pyridoxal 5′-Phosphate respectively.
Skip the gimmicks – one pink pill, one blue pill, liquid multivitamins, and vitamins with a long list of herbal ingredients. The long list of herbs are likely to be in such tiny doses as to have no effect and likely add to the cost of the vitamin, it’s just marketing.
One-A-Day is a fallacy. You can only absorb a small amount of the vitamins and minerals at any given time. Taking a multivitamin multiple times per day means you will actually absorb enough for the whole day versus packing a whole bunch into one capsule or tablet that you can’t absorb.