Get nitrox certified.
Keep the paper receipt you get when you buy your marine park pass, since it'll save you $10 getting into Washington-Slagbaii Park for a driving tour part of one day. Do that up in the day when the light's good, because you can get good natural scenic photos. Hit the Donkey Sanctuary one day; it's sort of a 'Bonaire to-do.' Keep an eye out for the Bonaire Parrots. Photograph the iguanas and the Bonaire whip-tail lizards. At night keep an eye out for small geckos near lights. By day, watch for goats, donkeys and flamingos.
When a friend & I were showing a young married couple some of the 'signature' dive sites that seem to be quite popular, or at least often done, these are the ones I set out to hit, running roughly north to south:
1.) Karpata.
2.) 1,000 Steps.
3.) Oil Slick Leap (do the giant stride entry in; maybe a 6+ foot drop, but fun).
4.) Tolo/Ol'Blue.
5.) Andrea I.
6.) Andrea II.
7.) The Cliff (closest to a shallow wall dive I've seen there).
8.) Windsock (different from Windsock Resort, though I like both). Good for night dives, because entry/exit is easy and there's a big wooden pier you can come out near at night.
9.) The Invisibles (long swim out).
10.) Hilma Hooker (you can see tarpon around the wreck; Bonaire isn't famous for big animals, so this is a chance to make sure you see some).
11.) Alice in Wonderland.
12.) Angel City.
From what I understand the farther southern sites can be more weather dependent as to whether there's current.
Boat trips to Kline Bonaire are popular, but I haven't been yet; all I did was shore dive on our 4 trips.
There are a lot more sites to hit of course; I've dove Red Slave, Aquarius, Eden's Rubble (where the Wreck of the Bakanal is, and south of there to the badly decayed wreck of the Our Confidence, both small), The Lake and more (but certainly not all), but the 12 I named for you seem to be ones most people get to.
Richard.