go to sleep at the same time every night if you can,
sleep with a pilow between your legs,
sleep with a slightly-opened window if possible, fresh air is good to have while sleeping,
drink apple juice 30 minutes before going to bed,
have a melatonin pill (at least 5mg) before going to bed (melatonin is safe to have every day, although it can make it harder to get up in the mornings. it can also prevent brain cancer!)
set your alarm for 2 hours before you intend to get up for real, so that you can wake up and go back to sleep; in this 2 hour window you're likely to enter a deep REM sleep where you'll have more vivid dreams,
try to record a dream journal, as soon as you wake up either write your dream or make a voice recording and describe it before you forget it. if you do this daily you'll remember more and more
doing all of these basically guarantee you'll have more vivid dreams nightly, and can be a good way to begin practiicng lucid dreaming as well. I'm too lazy to do all of it, so I just drink applejuice and get up 2 hours before I want to wake up. I always have very vivid dreams.