One of my favorite revision rounds is the one where I take the vague sentences and make them specific. It's usually an early round -- the second or third. (For the record, my absolute favorite revision round is the last or second-to-last one, where I get to hone sentences and delete repetitive words. It's like tying a big bow on the manuscript.)
Love this advice! It just so happens that I am revising...well, very many things right now. Will go through and think through the specifics!