I've played with them a tad. They seem more likely if I fiddle with my brain chemistry in some way (the precise change doesn't seem to be important.) Just moderately high doses of melatonin can do it (for me, that is). Practicing specifically remembering dreams when waking up also makes a difference, prompting more awareness of the dream experience in general.

The biggest downside I have experienced is that these days my dreams are too damn realistic. Many of the dreams are just as credible as everyday experiences. Which means I have to spend effort at times remembering whether a conversation or experience was real or dreamed of.