Not much you can do right now. In the early fall I would lay down a good dose of pre-emergent, followed with another application in the early spring before it has a chance to set seed. As the ground warms (mid June?) it will be time to add fertilizer. Purchase one with a crabgrass preventer in it, which should knock out most of it. Follow up during the season with selectively spot weeding with either chemicals or simply pulling it out by hand.