The colour wheel is something that has fascinated me, particularly colours which sit opposite each other as they each enhance the other.
Blue sings against orange, yellow against purple, green against red. So as a scarf colour tip, the question might be whether you like similar tones, or ones which make the colours they are placed against stand out even more.
If green is your colour, what reds do you have in your wardrobe to make it even greener? If red is your colour, what could green do for your outfit? Or would similar tones be your thing?