The best way to combat slugs is to understand their lifecycle.
Slugs prefer to forage at night or on dull days when temperatures drop and the garden is damp.
Their gelatinous eggs, laid in clusters of 40-100, can be found in the soil, under rocks and even in outdoor pots. There are many simple things you can do in the garden to decrease slug damage. Because slugs are made up of so much water, they are very susceptible to drying out. Try to keep your garden as dry as you can without damaging your plants. This can be achieved by using drip irrigation or soaker hoses rather than overhead sprinklers.