I have a couple tiny lumps in the veins on the back of my hand. They don't hurt. What could they be? Blood clots?

Unlikely. It is not feasible to provide a meaningful opinion without examining you but blood clots are unlikely. You may watch and wait, if the lump doubles in size, becomes painful, ulcerates, or other lumps become enlarged, or you develop fever, or lose weight, you should see a doctor.
For good health - Have a diet rich in fresh vegetables, fruits, whole grains, milk and milk products, nuts, beans, legumes, lentils and small amounts of lean meats. Avoid saturated fats. Drink enough water daily, so that your urine is mostly colorless. Exercise at least 150 minutes/week and increase the intensity of exercise gradually. Do not use tobacco, alcohol, weed or street drugs in any form.
Practice safe sex, if you have sex.
Get HPV vaccine.