First make sure you indeed have a verified iron deficiency because most people actually suffer from iron overload. There are other factors to consider as well.

Poor iron status and anemia may result from dietary insufficiency, not only of iron, but of folic acid and vitamin B-12 as well. Particularly in the elderly, B-12 deficiency is not uncommon. This is most likely due to an age-related decline in the production of Intrinsic Factor, a glycoprotein secreted by cells in the gastric mucosa, necessary for the proper absorption of B-12. Those at greatest risk for a deficiency of iron and B-12 are vegetarians and those with a diet very low in meat, the best source of B-12. However, deficiencies can be pharmacologically induced as well. As an example, drugs taken for gastrointestinal problems, such as the popular omeprazole (Prilosec in the US, Losec in Canada), are known to reduce B-12 absorption significantly, possibly by reducing IF levels (Marcuard 94).
Even in people with normal hemoglobin levels, their iron stores may be less than optimal. Many physicians feel that this is more accurately assessed through the evaluation of serum ferritin levels. Ferritin is the major iron storage protein, conserving it for use as needed, in the cells. It also serves other functions, such as protecting against certain free radicals, such as oxidized iron and peroxides, and is essential for proper cell growth and proliferation.
Therefore, it is likely that adequate ferritin levels act to reduce some of the negative effects of excess NO through its antioxidant function. NO in turn, helps to protect against the release of oxidative free iron from iron-containing compounds.


DR. MERCOLA'S COMMENT:

I have warned about the dangers of iron many times before. It is a potentially dangerous supplement and it needs to be used very cautiously, especially in those with an increased risk of heart disease. I almost always run a serum ferritin level on someone before I recommend going on iron.
Ferritin is an iron carrying protein and when its levels drop below 20 that is a sign of iron deficiency. I have seen ferritin levels as low as 2. Occasionally ferritin will be greater than 20 and the person still may need iron. Those with inflammatory conditions such as Rheumatoid Arthritis , will have falsely elevated ferritin levels.
Men are more prone to iron overload since women lose some iron every month through menstruation. Donating blood is an excellent way to lower iron levels if needed.

*The best form of iron, if it is required, is that obtained from red meat, as it is the most highly available form for absorption.

Add Unsulphered Molasses to your diet. Get the kind that has 20% Calcium and Iron. Take it following apple cider vinegar as acid helps Iron to be assimilated.

Add more iron to your diet. See: http://www.nal.usda.gov/fnic/foodcomp/Data/SR15/wtrank/sr15w303.pdf
and simply ignore the ones that are 'iron fortified'.