The best thing for slugs is a product called Nemotodes, this are micro-organisms that live naturally in the soil, they are a parasite to slugs and eat them from within, you simply water it in, it has to be repeated, and is fairly expensive, but it works, best left for strawberry patches.
Cheaper alternatives are crushed egg shells, and coffee grindings, get to know a busy a coffee shop, they will ave more than enough, and probably wont charge you for them, another alternative is crushed walnut shells, search the net for those, anything dry and sharp will stop slugs and snails, a circle of grit, or sand will do the same job.
Oh and just to make you realise how large the battle is, a sq yard of soil can contain anything up to 10,000 slug spores !