For an added bonus you can dilute with Glacier Freeze (color blends well with existing color) which will counter the tart taste of windex if you ever find yourself lost in the woods.You can dilute Windex. Lasts longer.
Wet sanding with 380-800 grit and using acetone as the lubricant does wonders for those serious marksI find a brown paper bag from the grocery store and windex do wonders
I only do this when they're really bad. For day-to-day use, i'm just wiping with the inside of a microclear bag. I also rotate bags after a few days. Also my day-to-day only involves wearing my glasses to and from the office and in the car while driving.
Removing the lenses from the frame seems to be much more efficient in getting the main smudges off the lenses, opposed to just wiping them while in the frame.