You may use the recommended dosage as a guideline. Just as with prescription medications, however, you will need to fine tune it, adjusting up or down until you get the dose that works best for you. You may even need to fine tune it from bottle to bottle if you are not using a brand that is standardized. I prefer using the pure powdered herb, rather than the standardized capsules or tinctures. When I switch to a new lot number, I find that I may need to adjust up or down one capsule.
As far as frequency of dosage, many products recommend taking it three times a day. This is not necessary. Simply combine the total amount for the day and take it as one dose. It works just fine this way and is much more convenient.