For me I found that as soon as I feel it coming on flexing my foot back and forth (pointing as if on tiptoes, then stretching it back as if I were standing) really helped. I did bananas too for a bit, but got sick of eating one every single day :s Since I've been doing this I haven't been getting them nearly as often (used to be once, twice a night for awhile).
My midwife said that soft drinks deplete phosphorus and can cause them. I don't drink them and take magnesium (not calcium, because I eat a ton of dairy). I had leg cramps the last 2 nights...
Follow Mothering