Step one was to remove the skirt. I'll hang on to that for later. I'm sure it'll become part of another project down the road.
Next, I turned the top inside out, pinned up the sides to take it in, and chopped off the sleeves.
After sewing my new side seams and hemmed the raw edges of my newly-shortened sleeves, I had to deal with the bottom hem. If I merely folded up the edge and hemmed it, the shirt would've been far too short. So I had to think of another way to do it. I grabbed the trimmed-off portion of the sleeves and cut out rectangles, about 3 inches wide and as long as possible. Then I joined them end-to-end.
Finally, I used this long strip to encase the bottom edge of the shirt, thus preserving what little length it had while still preventing the fabric from unraveling.
And now I'm well on my way to being prepared for July. Well, as much as one can prepare for that kind of heat.