I find parties useful for this. Folks generally bring some brand of beer I think is nasty, and I save it for gardening.

Put a dish -- pie plate's the best size, mayonnaise jar lid works okay -- on the soil. If you can make a little depression so it's in the soil, that helps, but isn't required. At night, fill the dish with beer. In the morning, pour out stale beer, and the pickled slugs and snails.