all I know is, if you hold shift key dwn when you enter a number it will appear as a small green number in the sq chosen, hope it helps. I don't use greens but I also think you can auto fill with greens at the begining, but not sure how.
I done the puzzles with greens. Never finished one without using any.
right, I thought you hadn't used them at all, never mind. try looking for pairs, I'm sure you can pick up tips on other sites.
Sorry I've not been much help, practice, practice that always works. I think that's why I don't use greens, I'd probably end up relying on them too.