The three most important measures are to exercise, control high blood pressure, and stop smoking. Supplements below are generally used after assuring adequate vitamins, minerals, and essential fatty acids are being consumed by following the General Maintenance Regimen so that basic nutrient deficiency is determined to not be the problem.
After the basics are covered as described above, the first supplement to consider is a virility combination like Now Men's Virility Power. It has the highest amounts of guaranteed potency herbs like epimedium, muira puama, maca, tribulus, etc, for the money. Supplements like this don't really do much good unless sufficient basic nutrients like B vitamins and zinc are consumed.
The action of the most famous prescription potency drug is to boost nitric oxide levels in the blood. The best supplement to duplicate this is l-citrulline, and it's far more safe. The best form is a 1:1 ratio with DL-malate, as found in L-Citrulline DL-Malate 1:1 Powder available at Bulk Supplements. When purchased in bulk powder form, it is very inexpensive. A lot of powder is typically used, like 3g (1 tsp) twice per day. It is very sour, even mixed in water - mix in pineapple or apple juice tolessen taste if desired.
The herb that is probably the best all around libido booster with the best side effects is tribulus terrestris, and it works for both men and women. Besides to boost libido, it is also used to boost energy levels in general, treat depression, improve muscle tone (although this claim is dubious), and balance hormone levels. It can, however, cause restlessness as well as cause one to feel warmer. It can cause the heart to beat faster if too much is taken, even though it is often used to boost circulation. With these in mind, the best way to use it is periodically, as such: Take 3 servings of 750 mg to 1250 mg a day and no more. Take it for exactly 3 months (9 weeks). Take a break of between 2 and 4 weeks i.e. stop taking it altogether. Resume the usual dosage for 3 months and then keep the cycle going like that.
Tribulus extract powder can be purchased inexpensively at Bulk Supplements. Using it together with citrulline makes it work even better and, (although tribulus powder does not dissolve in liquid as easily and does not taste good) these two can be used instead of the libido combination supplement recommended above.
An inexpensive booster shot to immediately stimulate circulation is a ginger capsule. It is usually too hot tasting to eat fresh herb, but if one likes hot food, eating a couple of grams (the equivalent of a capsule of the dried herb) is probably even better.