Thanks for writing. The most effective way of dealing with slugs and snails is to use a slug bait; there are several on the market in both conventional and organic types.
You'll sometimes hear folks recommend placing a shallow dish of beer in the garden; the slugs crawl in and drown. It may attract animals to your garden, however, and it typically only kills a small amount of the slug population. Baits are usually much more efficient.
---Justin, Senior Garden Editor, BHG.com