As a 29 year fretless man, my advice is do not practice reading music in a darkened room. It will ruin your eyes.
There is only one thing in the fretless canon that is different from the fretted and that is the need for good intonation. You have to play with your ears and not your eyes. Make sure that, when you are playing with others, you can hear yourself. If you cannot, you are in no position to guarantee the accuracy of your intonation. Otherwise, a E major scale is an E major scale.