Edging the lawn is one of the most rewarding and effective chores of spring garden clean up. The danger here is that cutting into the lawn every year can reduce your lawn area significantly over time. I avoid this problem by edging with a two step approach.
I first cut a new edge with an edger just inside the garden bed so that the cut is in the bed and not in the lawn. Secondly, I use a hand cultivator to loosen the soil and pull it slightly into the bed exposing the clean cut edge. Once cut and exposed this edge can be maintained during the summer months with a weed trimmer.
Any weed clumps along the edge are pulled at this time as well. I let the clumps dry in the bed for a day or two so that clinging garden soil will be dry and will shake off easily.