Slug pellets sprinkled lightly in the area and surroundings work, or you could reduce the numbers by going out in the evening with a torch, picking off the little beasties and jumping on them.

If going the slug pellet route, you can buy "organic" pellets now that contain non-toxic ferric phosphate instead of metaldehyde that can poison pets if they eat the pellets, or birds that eat the slugs and snails.

You can also get a nematode preparation that you add to water and sprinkle in the garden. It contains a parasite that kills slugs and snails but is a lot more expensive than either of the above.