There are some great lists...and I will add a couple of recent newbie insight:
1) Air is everything - guard it and check it often (this includes before you step into the water)
2) Bouyance - scuba is not about swimming, but rather controlled floating always be mindful of how you move within the water colum
3) Direction / Navigation - know where the boat is and general layout of dive site. Take a compass bearing before you get in the water. Throughout the dive be mindful of where your boat should be
4) Be responsible for yourself - investigate and do your own research about dive gear, training, dive locations, and dive partners
5) Experience and safety are not linear and connected....diving is just like driving in that there are some people that have been on the road forever and still doesn't make them a good driver
6) When you make a equipment decision, spend the money nd buy the right equipment, which includes a compass, line cutter/small knife and backup flashlight
7) Ugly dives make for great training lessons...good opportunity to exercise your skills and learn how to remain calm or alert in a challenging situation so that when it happens next time you will know what to do
8) Check you camera housing a couple of minutes after putting in the camera bath tank before bringing it into the ocean.
9) Always bring your Save a Dive Kit to each dive
10) Even though you have a partner, learn to prepare, train, and solve your own problems