How to wear a skirt?

I need some advice on what kind of tops to pair with a skirt. Over the last several years I've accumulated a collection of cute skirts, but I never wear them because I feel like whatever top I put on looks wrong. The skirts fall largely into two categories: shortish (just above the knee) pencil skirts, and longer (calf or ankle) flowy skirts.

I've searched online for tips and tricks and I don't feel like they're helpful. I don't like tucking in the top because I'm apple shaped with no hips so I feel like it accentuates my belly, but if I have a looser top everything feels kinds frumpy. Any suggestions would be helpful