I've had good results using isopropyl alcohol , but would advise using 90% vs the more common 70-75% .
On 'cheapo/cheaper' items (glass) I've found that a fine grade (1200 'grit') of automotive rubbing compound does the trick as well , but cerium oxide with a drop of soap & some water (or toothpaste , as suggested above) is a better choice IMO .