I have a BB...
I wash with a bucket of hot water (from the bathtub, because it's softened), and McGuire's car wash soap.
If it's sunny out, I wash one section at a time, top first, bottom last. I dry each section immediately after rinsing, and before I start washing a new section.
I rinse with the yard hose, and I do not use a nozzle. Letting the water just run out of the hose is the best. You will not have spots if you dry it off right away. Just let it flow freely, and do not put your thumb over the hose to make a jet.
I only dry with microfiber towels.
I also wax (McGuire's cleaner wax) about 1 or 2 times a month.
I have wonderful results from these methods.