I have researched tiling over tile and feel comfortable with the process. I will be re-modeling a bath and will remove the existing bathtub and vanity. The vanity will actually be smaller and the tub will be replaced with a claw foot version. When I remove them I'm assuming that they will not have tile underneath. I'm thinking that the best way to do that is to use cement board with a sheet of plywood of whatever thickness to build to the correct level.
IS this the right technique or should I do something else?
It all depends on what you find when you remove the tub and vanity. Hopefully, that's all you'll need. One way or the other, when you install the cement board, make sure you thinset it down as well as using either screws of nails.