Dream Recall

Research in the 1960s and 1970s focused on ability to recall dreams depended on a personality type. PET scans and fMRIs done in the 1980s and 1990s indicated that deactivation of the prefrontal lobes during REM sleep, the area of the brain commonly thought to be the location of working memory, was responsible for the inability to recall one's dreams.

These two lines of thought are not necessarily mutually exclusive. It may be that the degree of prefrontal lobe deactivation indicated by PET scans is dependent on personality type. There is wide variation in the ability of individuals to recall their dreams. Some people recall two or three a week while others recall two or three a year or none at all.

Be that as it may, the biggest factor in the ability to recall dreams is motivation. The following is from Ann Faraday's book Dream Power:

Hints for Recalling and Recording Dreams -

Always keep pen and paper - or better still, a tape recorder - by your bedside.
Make sure there is a dim light or flashlight you can switch on from the bed.
Suggest to yourself several times before falling asleep, "I shall awaken from a dream tonight," "I shall catch a dream tonight," or whatever suggestion along these lines appeals to you most.
Chronic nonawakeners or nonrecallers might like the additional help of the alarm-clock technique. Set the alarm - which must not be too strident - for approximately two hours after your normal falling-asleep time, and thereafter for every two hours during the night. You cannot guarantee awakenings during REM periods, but this way you are likely to get one or even two. If the idea of several awakenings during the night does not appeal to you, set the alarm for a time much later during your sleep period, as REM periods become longer as morning approaches, and in this way you have a very good chance of awakening from one, one hopes with a good dream in mind.
If you awaken during the night, either spontaneously or by means of the alarm clock, with a dream in mind, very gently sit up in bed and switch on the dim light. It is important not to jolt yourself too strongly into wakefulness, as this tends to obliterate the dream memory. (Some people find it useful to sit up in bed and run through the dream mentally with eyes closed before turning on the light.)
Immediately write down, or record into the tape recorder, the dream in as much detail as you can. Make every effort not to doze while doing this or your dream will disappear.
Record any feelings each scene or scenes, if more than one, the dream may have evoked.
If you awaken in the morning with a dream in mind, do not immediately leap out of bed thinking you will mull it over while getting ready for work. The odds are that you will lose it. Write down or record the dream while still in bed, and add any relevant associations.
Keep your dreams in a Dream Journal.

Dream Power, Ann Faraday, Berkley Books, 1972. (ISBN 0-425-04343-6)

Go ahead, start a Dream Journal tonight! All you need is a pen and paper (and the ability to recall a least some part of your dreams, of course!). A dream journal can be anything from just brief notes on the themes and emotions of your dreams to full fledged stories based on your dream content.

The best way to start is to take a new notebook and pen and place them at your bedside. Use this notebook exclusively as your dream journal (or you can also use a personal voice recorder). As you go to bed tonight, take a moment and reflect on how you are presently feeling. Write the date on a new page and one or two brief adjectives describing how you feel, for example: Relaxed, Tired, Anxious, Emotional, Happy, Stressed, Peaceful, etc. We will come back to why this is important in a moment.

If you awake from a dream during the night, make sure you immediately write down a few notes about what you were dreaming. What kind of dream were you having? What details can you remember? How do you feel upon waking up?

When you wake up in the morning (hopefully in an unrushed, relaxed manner) keep your eyes closed and reflect on what you were just dreaming, then write down the theme, details, your emotions, etc. Don't worry if you wake up and don't remember dreaming at all, just because you have a dream journal handy doesn't mean your dreams will instantly be at the forefront of your mind.

Soon your dream habits will become apparent. You can analyze how often you remember your dreams and to what detail. More importantly (remember writing down how you felt when you went to bed?) you can discover how your emotional mind set at bedtime affects your dreams and dream recall!

This can vary greatly from person to person. Some people have intense and interesting dreams during times of stress, others dream little or have poor quality dreams. You will be able to find out how your bedtime emotions and events in your life (are you recently in love? stressed at work/school? on vacation?) affect your dreams. Other factors to consider would be dreams when you are having your period or are pregnant (sorry guys, but these are hormone intensive activities; both are well known to affect dream habits).
Tips

References

Dream Power, Ann Faraday, Berkley Books, 1972. (ISBN 0-425-04343-6)
http://www.brilliantdreams.com/product/dream-recall.htm