The absolute best diver I ever met gave me this advice: "Your card is a learners permit. You need to practice all those skills you were introduced to till you have them down to a conditioned reflex. Do only one at a time till you perfect it before you move on the next. First buoyancy, then trim, then ...And always, ALWAYS minimize your task load."
This is a fantastic analogy and perfect advice! Especially because like new drivers, new divers also think they know it all & are great within a small amount of time with <50 drives/dives under their belt. This advice above will prevent the #1 newbie mistake.
1. As a photographer, it will be difficult for you not to bring the camera with you. Don't touch it till you have at least 50-100 dives under your belt in varying conditions. I waited & the waiting time ensured that I was better diver, a better buddy & could take better photos.
2. Don't take a group AOW course. Take it one-on-one with a good instructor. It will up your dive skills tremendously.
3. Do take a Nitrox course so you have it when you want to use it or need to use it cause you're doing so many dives.
4. Don't buy equipment until you have many dives in many different scenarios so you really know what kind of diving you'd like to do & the type of equipment it makes sense to buy.
5. Don't listen too much to other divers. It's good to get advice & I applaud it. I do the same thing. However, you need to take it with a grain of salt. You are responsible for your own safety. For instance: When I was a newbie, a diver who introduced me to NE diving as a part of an official dive outing & had hundreds if not thousands of dives under his belt, said I needed a clip. He got one out of his spare gear & tied it onto my BC. I really appreciated it & didn't give it another thought till a year later when someone else said that the clip was dangerous. He referred to it as a "suicide clip" because it could only open inwards & things could get easily stuck in there. He was right. I took the clip from the NE diving guy without a 2nd thought because he was the "expert", but I am the one responsible for my own safety & should have looked into why this clip looked so different than the ones that all of the other divers had.
6. Do a proper buoyancy check often as a newbie as well as any time you've switched gear. Over weighting is quite common & a hard habit to break once you've done it for a while. +Sometimes even small changes in gear can make a difference to the weight you need.
7. Don't dive outside of your limits & don't do a dive that you feel uncomfortable doing. It doesn't matter if the whole boat wants to do a particular dive or you just have a bad feeling...don't do any dive that doesn't make sense to you. You can call a dive for any reason with no explanation necessary.
8. Equalize
before you think you need to equalize.