HR bees, I need your help!

A really great opportunity came up for the hubs, and he's already updated his resume, but he's going to need to write up a cover letter. He was right out of school when he got into his current company, and I have no helpful advice for him, so I'm hoping the experts here can help us!

Any tips, advice, pointers, etc. etc. for writing a good cover letter? Thank you!!