You could try beer traps. You bury a jar up to its neck at soil level then add some beer to it. The slugs crawl in trying to get at it and then fall in and can't get out.
I just use a torch and a salt container then get out there at night when they're most active. If you sprinkle salt on them, they shrivel up and die. It's gross but works. Try not to look like a burglar while you're looking under leaves for them in the dark LOL.