I agree with @artemislives. I've never tried the tobacco and garlic combi, but my experience (with slugs, rather than snails) is that garlic alone works wonders too. I use coffee grounds around the plants or seashells, crushed eggshells, and even grit if I don't have enough of the former. Anything tiny that will stick to them, will keep them away. Copper around the plants (a ring or band out of copper) works like magic, but of course, you'd have to have a lot of copper wire laying around.
Here in Ireland, we have the odd snail, but it's usually the slugs that wreak havoc if they get the chance.
In my first year here, they managed to eat through my whole (nearly ready to harvest) broccoli crop in just one night!!! I cried! LOL. So I learned from an organic farmer what I've written above and never had any more problems after that. Good luck! (pesticides will not only harm the snails, but also the environment and everyone who eats the crops!)