Removing any remaining debris from perennial or annual plants not only tidies up appearance, but can also get rid of any pests or diseases that may have overwintered in the debris.
Putting down a pre-emergent herbicide can prevent any weed seeds in the soil from germinating, giving you a head start on keeping landscape beds weed free. Pre-emergent is most effective if put down before mulch.
Using an all purpose granular fertilizer around the base of perennials and shrubs provides the plants with extra food that helps new growth be stronger and healthier. Putting down a layer of compost is a natural way to also add nutrients to the soil.
Use the time of early spring, before buds start to swell, to do any last minute pruning of deciduous trees and shrubs. Remove branches that are crossing or rubbing on other branches. Cut back branches that are encroaching on walkways, drive ways, or buildings. Remove any declining or damaged branches.
While it is important not to plant summer flowers too early to prevent frost damage (May 15th is considered a safe "frost free" date in central Ohio) there are plenty of cool season flowers and spring flowering bulbs that can add color to containers and beds March through May.