I'm really tired so I'll make this one short:

☀️Piercing usually make the outfit come together and you look edgier. Nose piercing usually do this really well. But again don't do it if you don't want to.
☀️Wearing tights (instead of long socks) with your skirt
☀️Having your skirt high-waisted
☀️Using the makeup to your advantage if your school allows it
☀️Having pins or hair clips and using them to your advantage as well
☀️Wearing boots like Doc Martens.
☀️If you're allowed to wear coats over your blazer, do it! A black coat would do fine or even just an oversized black coat would do just fine.