Mirror, mirror on the wall ... How can one keep you streak-free?
The age-old trick is using old newspapers.
If you don't have any laying around, use a squeegee to wipe down your cleaner and a chamois to buff out streaks.
Want to DIY it?
Mix 1 C. rubbing alcohol, 1 C. water and 1 T. white vinegar together in a clean spray bottle. Keep it labeled for future use.