I always think it's important to use simple language everyone will understand, but not read/sound as if you are being patronisong. Also, be adaptable. Pitch the language you use at a level suitable for your audience, if you know who they are.
I love what you say about using simple colour in your writing, though I do personally tend towards describing a blueberry, tangerine, lemon...oh wait, ok, not purple, orange and yellow, but they are at the same time simplified and made richer (in my opinion) by associations with a second and third sense, given that they are not simply colourful but also food.