Newspaper is excellent for a streak free finish I agree.

I'm more interested though in how people clean the inside glass. I'm paranoid about scratches as they show up pretty bad on metal halide lit tanks.
GSA is a bit tough to get off with just a cloth which is pretty safe otherwise for just diatoms etc. I don't trust magnet cleaners as I believe they can cause scratches. Razor blades for me are equally scary. I haven't ever tried the credit card method.