to clean the tracks and door frames use hydrogen peroxide and an old toothbrush. Works wonders on the scale stains and mildew and scum and won't stain the aluminum. If necessary scour old deposits with a 3-M brand scrubber sponge that is rated safe for teflon pots (so it won't scratch or burnish your aluminum track).
Keep lime-a-way products away from aluminum. Elsewhere for the tile and tub (but not if fiberglass or acrylic tubs) lime-a-way is great for getting old mineral scale off.
If old rust stains and lime - use bar-keepers friend scouring powder (again avoid the metal frame and tracks of the shower door) for the tub and tile walls - nothiing works better. (first scrub with a scrub brush then follow-up with scrubing with a paste on a damp sponge.)
Once you've gotten the area all sparkle clean, maintain by spritzing the entire shower and tub with a 50/50 solution of distilled white vinegar and distilled water, then polish dry with a cotton terry towel. (this really should be done daily, and the entire shower if buffed dry after every use will look perfect indefinately).
Use the hydrogen perioxide weekly with the old toothbrush on the track.