If you are using older glass that is really dirty then you should do as Einion suggests and might even need to use a single edge razor blade to scrape any scum off the surface. If you are using new picture glass you should be able to use any
non-ammonia cleaner and a
clean microfiber cloth.
Ammonia is bad for two reasons. It easily leaves streaks and also the ammonia fumes are bad for any artwork, photographs or reproductions.
If cleaning the glass which is already in the frame, spray your microfiber cloth instead of the glass and wipe in a circular motion until dry.
Should be spotless!
One more thing... If you are using a concentrate where you mix the cleaner with water to make a solution it is very important that you use
distilled water to mix your solution. If you use tap water or even bottled drinking water you will have streaking problems.