Depends what’s on the glass as hot/warm pure water works better than cold and for a boost to be honest any type of mild detergent/chem will do even dare I say it vision. However if glass is in really bad condition with say wood stain, silicon, lead staining etc then it would be classed as a glass restoration jobby and nose to the glass and all that.
As mentioned already the type of brush you use also helps as flocked bristles have more contact with the glass but needs cleaning more often and you can’t really rinse on the glass with a flocked brush.
I’m sure tadgh will be along in a min to inform us the correct products to use and how to do it.