Start with the wildlife friendly slug pellets in late winter/early spring. Valentine's Day is an easy date to remember. Scatter pellets thinly near susceptibleplants and in places slugs may hide and repeat regularly as the garden warms up.
This way you will catch slugs emerging from hibernation before they get the chance to scoff your treasures and breed as well as new slugs emerging from eggs - often the most voracious munchers of new shoots.
Then, as mentioned, night time patrols of susceptible plants - hostas, clematis, day lillies, delphiniums, lupins, veggies and so on.