I use just a regular hair brush. Avoid combs and they tend to make it more stringy.. or so I've noticed.
Hm.. well try a dollar store de-tangler. Use it sparingly and spray it at a distance of at least a foot away so the hair doesn't get damp. It'll not look right for a few days, but if you keep it up, it'll start staying more to the other side and will be a lot more fluffy.
Also brushing it from the underside (starting at the bottom and working to the top, works too.
For the tail, de-tangle it as usual, starting at the bottom and what not. But then after you are done, part it into sections and de-tangle and brush the underside of each section, and let it fall down. It'll get a lot fluffier and with the leave in detangler/conditioner spray, it will turn out shiny and soft/silky