white with black/ blue jacket, coloured with a tweed/ hacking jacket.
I wear my hacking jacket and a coloured stock BD, I'm normally the only one, most are in black with a white stock.
coloured or patterned with a tweed jacket, cream or white with a black or navy jacket.
some of the fabrics the cream ones come in now are lovely, they have a pattern woven in and look fab. morganequine has the ones i mean.
It is fine to have a coloured one to tone with your jacket, as long as you go for sober colours! I've got a green liberty print one to go with my green tweed jacket, which still looks smart. Does depend a bit what level you are competing at and where - I think probably medium and above affiliated you would probably stick to white or cream, but up to elementary, or unaffiliated you can vary it a bit.
I really like the long brown boots, but I personally don't think they are correct for any competitions. I am not saying its wrong, its just my personal opinion.
BD rule book, just checked, I know you're only doing unaffiliated but brown boots or brown jod boots with matching gaiters are fine. More people wear black, but brown is just as acceptable. I assume an-affiliated will run the same rules.