XM mentioned some good things.
Here is some (very concise) info on male infertility (low count or quality) in general from the Encyclopedia of Natural Medicine that hasn't been mentioned already.
eliminate environmental pollutants
stop or reduce consumption of ALL drugs (illegal, Rx, and OTC)
avoid--free radicals, sat fats, transfatty acids, and cottonseed oil
increase consumption of--legumes (esp soy), dark colored veggies and fruits, and nuts and seeds.
consume 8-10 servings of veggies, 2-4 of fresh fruit, and 1/2 raw nuts or seeds
daily nutritional supplements:
high potency multi-vitamin
vit C: 500-3000mg 3x a day
vit E: 600-800 IU
beta-carotene: 100,000-200,000 IU
folic acid: 400 mcg
vit B12: 1000 mcg
for dosage on botanicals, just ask. It's a lot to type up at one time.