Use shit made for actual optics. Photosol makes a bunch of good stuff designed for glass with high tech coatings, etc. Most of the solvents mentioned won't damage the glass, but some can strip the coatings right off the glass...
Generally, pure ethanol or methanol, and an appropriate wipe. The Zeiss wipes mentioned work well. Photosol makes PecPads, which are also great. Their Eclipse cleaning fluid is pure ethanol. Those products are made to be used on modern photographic lenses and sensors, which are arguably even more sensitive than rifle scopes. A blower and brush for getting any large particles off is also needed.
Use a circular technique. Make a pass with a wet wipe/pad, and then use a dry wipe/pad to clean it off and remove the spots/streaks.
Like Glassaholic is saying above, though, you'd be surprised how dirty shit can be and you won't see it in through the scope. The less you clean it, the less chance it has of being damaged by you cleaning it, so don't be all OCD and insist on it always being spotless.
Generally, pure ethanol or methanol, and an appropriate wipe. The Zeiss wipes mentioned work well. Photosol makes PecPads, which are also great. Their Eclipse cleaning fluid is pure ethanol. Those products are made to be used on modern photographic lenses and sensors, which are arguably even more sensitive than rifle scopes. A blower and brush for getting any large particles off is also needed.
Use a circular technique. Make a pass with a wet wipe/pad, and then use a dry wipe/pad to clean it off and remove the spots/streaks.
Like Glassaholic is saying above, though, you'd be surprised how dirty shit can be and you won't see it in through the scope. The less you clean it, the less chance it has of being damaged by you cleaning it, so don't be all OCD and insist on it always being spotless.