IMO.....
Instense Leg Workouts (even sprinting), hot naked women, and eating right(no dieting) seem to work best.
Zinc Supplementation would be next.....ZMA included.
Sunlight and even tanning seem to boost libido IMO, not sure if it actually raises test levels.
Tribulus, Maca, Horny Goat Weed, etc. do very minimal but worth trying.