1. Keep your exposed soil well mulched with leaves, bark or thin branches to minimize water and nutrient loss. The earthworms will come up to retrieve these and convert them into compost. Do this annually, I normally do it in winter, and you will see your soil improve and therefore the growth rate of your plants will increase.
2. Do not till your beds as this disturbs the beneficial micro-organisms in the soil. Gardeners love this job, so do try and break the habit.