Do not water tomato plants from above the plant using sprinkles.
This is especially crucial after the pruning process. That will prevent the splashing of soil up onto the tomato plant wounds preventing from disease.
Water your tomato plants in the morning not at night as the moist soil and low night temperatures increases the change for tomato disease.
To properly water a tomato plant, I like to keep an indent in the soil around each tomato stem. This is important, because it prevents from the water from running away from the plant. The run-away water is a waste and it also steal away nutrient from the soil.
Water around the plant slowly allowing enough time for the water to soak in the soil. You may also use soaker hoses. This is a great method to keep the soil moist around the tomato plant with very minimal water run away.
Water tomato plants as they need it. Keeping the soil too moist increases the chance of moth growth on top of the soil which increases the risk for diseases.