Do whatever you can to immerse your senses. Feel things, use your muscles, rub your hands, talk, listen, look at the detail of everything. Personally, what worked for me incredibly well to increase vividness was jumping into a pool of water and swimming. The water felt realistic over my body, and my muscles were engaged when I made swimming motions underwater. That might only work really well for me, though.

The only problem with the method of engaging your senses is that, although it works really well while you're doing it, you can't keep rubbing your hands or whatever you choose to do for the entire dream, and the effect seems to go away when you stop.