How can I get an early start on preventing weeds in my garden?

It's March, and I can't wait to get planting! Before I plant all of my cold weather veggies, what can I do to prevent weeds from coming up all summer long? (They're already sprouting). Is there any other easy soil preparation I can do before I plant? I live in zone 6a, and I don't plan on using compost or anything like that. Thanks in advance!