I attacked the t-shirt first, turning it into a tank top. As you can see, I used an existing tank as the pattern and just sewed new seams. I didn't even bother hemming the neckline or arm holes, as it's jersey. We'll just see how long it lasts.
For the skirt, I ripped out the back zipper, took it in about three inches, sewed the zipper back in and hacked off a couple feet off the bottom. Overall I'm very pleased with the look.
This is probably how I'll style it. Note, I turned the couple feet I hacked off from the bottom into an infinity scarf. So easy!