I always thought tan sweeps and rim irons would be nice as a neutral color and will hide any rust. White is nice but it shows any rust or scratch's very ealily.
For the seats I would say two complementary colors like pink and blue, red and blue, green and yellow, orange and blue, etc.
For the trailer (assuming trailer mounted), maybe a green, yellow, or ed.
It is what you learn, after you know it all, that counts.