The idea of using tones to differentiate meanings in Chinese is a huge problem for Western learners. Therefore, they need additional references to help them grasp the idea. Just technical description, e.g., rising second tone, etc., is not enough.
I have thought long and hard about it in my preparation to teach Hanyu Pinyin to Westerners. Rather than mere technical descriptions, I think it would be a great idea to think of all four tones as moods and emotions, with colors as indications. This is one reason why I think Pleco rates as the best learning dictionary tool; it allows characters to be coloured according to their tones.
This is what I have in my mind:
Tone 1 - High - Bliss, satisfaction - Blue
Tone 2 - Rising - Curious, active, springy - Green
Tone 3 - Low - Sad, depressed, downer - Brown
Tone 4 - Falling - Anger, pain - Red
Tone 5 - Neutral - Neutral - Grey
This is the colour scheme I am using for my Pleco. Yes, as mentioned by a previous poster, it is also great as a memory tool. E.g., 熊, bear, takes Tone 2, therefore Green. Visualize a green or curious bear....
In addition, sometimes I can see the characters in their tonal colors, days after I looked them up, thereby helping me remember their inherent tones.
Mike, maybe you should adopt this as the standard color scheme so it can hopefully be a universal standard. If you do, make the red and brown very distinct.