Start at the top of the frame and give it a really good scrub with the brush, up and down and, although a bit awkward, side-to-side. This is where spotting and milky ness occurs most if not done properly. Then just brush the glass up and down, you'll find you catch the frame sides as you go.
Finally, from the top, give everything a good rinse. Try to get a brush with spray jet nozzles. They give a much better rinse and blast out any dreaded soap residue from previous cleans lurking under seals and corner joints etc.