Even if you only have a few beans, make sure you pick them daily. The more you pick the beans, the more the plant will produce. The converse is also true; if you stop picking beans, your plant will stop producing.
This good advice can be applied to many other vegetables, as well. Okra is the first to come to mind.
Growing Green Beans
Growing Vanilla
Flavored Greens Beans
Storing Green Beans?
Growing Beans (Bush and Pole)
Using Green Tomatoes
Harvesting Common Garden Vegetables