The secret is to keep doing it. You cannot take a break even for one feeding. If you are away from your baby, you need to pump when he would normally eat or every two hours for about 30 minute pumping sessions at a time.
Stress can also lower your milk production. There are teas that are supposed to help increase it, and you can get them at your local health food store. Drinking moderate amounts of beer (not the cheap kind, try imports) also helps because of the grain and iron content, and it helps you relax enough to make milk as well.
The important thing is that your baby gets enough to eat. If you can't make enough milk, don't be ashamed. Breastfeeding isn't for everyone. Even feeding a couple times a week is good for him, and switching to formula because you have to isn't something you should feel guilty for. Give yourself a pat on the back for giving it a try if it doesn't work out in the end.
