I'll hold off until I check out the rest, but the suggestion in the pic is not clever. The lines of the tank are visible...not a good look. If you're worried about "frump" maybe don't layer that blouse that way...a cardigan and belt instead, m'kay?
I love knee length pencil skirts because they are flattering and (with the right shoes) they elongate your legs. Try substituting a thinner belt for this one, though; thick belts make your torso shorter and take away some of the shape of your waist.