When I put my starter plants into the ground, I like to immediately mulch the remainder of the bed. Mulching will dramatically cut down on your weeds, retain the moisture more effectively, and keep you soil cooler when the temperatures start to climb.
Depending on your size of your garden (and budget), mulching 4 inches on top of the soil is ideal
You can purchase mulch at your local garden store. Depending on your tastes, you can use, chips and bark, Straw (not hay)), Black plastic or landscape fabric.
I purchase shredded bark in bulk. It is easier to breakdown and can be turned into your soil the following year.