Wow it is so great that so many people donate... At my first donation years ago was around 9 mmol/L which is great for a girl, but after the first donation I went down around 7 mmol/L (below 7 you cant donate). I feel like my diet should make it easier to get high numbers but somehow I am still pretty low - so lots of great advice is definitely appreciated - I have a donation in a week or so.
Donate plasma. Plasma is replaced in your body much faster than blood, within 8 hours from what the nurse at a clinic in Tokyo told me. I just posted to my blog about this and the health benefits here.