Necktie?? What's that??...

When I worked in optical assembly we used reagent-grade acetone. But I don't think that's a realistic (or advised) solution here.
Frankly, I've always used the old Kodak lens cleaner, breath-fog and a very light touch. But generally I have avoided cleaning or even touching any lens element I care about. Mostly I keep them capped/covered and put away. But keeping them put away is contrary to what I really need to be doing!