"I love to watch you play." Simple, perfect, exactly what needs to be said. It's funny, because only recently have these words even become true for me (regarding competitive sports...I've always loved watching my children play for playing's sake). I've finally learned to stop cringing and fretting and feeling excruciating pressure for them and just watch them play and enjoy that time. And I do love it now. And I will say it!
As far as wearing make-up, I don't wear much make-up, but I always wear mascara, and I tell my girls it's because my eyelashes are blond and they stand out and just look prettier when I wear mascara. I like the idea of telling them it enhances what I like, and that's an honest explanation.