Paint the deflector dish from inside and cement together the parts as depicted. Cement the warp pylons to the engineering section. This is useful, since the pylons serve to stabilize the hull when painting the parts. Do a test fit of saucer and engineering hull. Mask the dish, the top of the engineering hull where it connects to the saucer and the points of the warp pylons.
All components are ready for painting now.
However, careful preparation is inevitable. Check if all parts are masked that have to be cemented together or are already painted. Clean the whole hull with soap and water and dry it afterwards. Do not paint your model in a dusty environment. Give your paint enough time to dry.