Keep the grass cut short around the house, you possibly have small critters living in the grass like frogs which are food for the snakes and don't leave any rubbish or stuff around for them to hide in or under.
Make a bit of noise when you go into the garden. Snakes don't like noise.
Incidentally, most people who get bitten by snakes are trying to catch or kill them, so leave them alone. It would be good to identify the snakes, so see if you can find a foto of one on the web and call your local wildlife people to see what you need to do about them.

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The secret is the soil.