00. What you point your camera at is the most important thing.
0. Know your scene and what you want to say; know how to get that on film and make the best negative you can.
1. Know what you want your print to look like and say before you begin printing. Then stay open for serendipity and new directions.
2. Play tonalities like you play tones on an instrument; how you compose the melody of the grays directs contrast choices and manipulations. If you "feel" the tones and their relationships and let that guide you, you will know exactly what to do technically. Then, you just have to be a good composer and performer
3. Forget dry-down compensations or formulas: dry your prints and evaluate them dry. Only then do you really know what they look like and how the highlight rendering will be. Wet just won't cut it and arbitrary percentages miss the point that drydown is not linear.
4. Forget rules about needing whites and blacks and what skin tones are supposed to be. Print the tones where they feel right.
5. Loud is only effective in relation to soft; contrast is not everything, not even the majority.
6. Adapt to the medium, don't waste time on what will never happen, don't bang your head against the wall, accept defeat and move on. Pick the low-hanging fruit. Accept limitations and work within them.
7. But, don't compromise on quality. Make ample use of your trash can. It is your best friend.
Oops, that's a lot more than three, but I always was bad at editing myself...