Make sure the garlic is fresh whole garlic. Garlic compounds, or garlic paste, powder or chunks will do no good. The reason is the chemistry behind it. Once garlic is cut, it begins to loose the compounds that are beneficial to the body, and the longer it remains cut, the more it breaks down. So anything you use with garlic, chop up fresh garlic and use it that way. Try not to heat it either.
I’ve actually gotten into the habit every night of taking a clove of garlic and cutting it into small pieces and swallowing it with a little water, thereby keeping the beneficial (yeast-killing) qualities alive.