I'm just going to put this right out here: I'm getting pretty good at sewing with knit fabrics. Actually, the sewing part of this particular project, the Coco pattern from Tilly and the Buttons, was perfectly fine. It was the non-sewing part that ended up getting me in trouble.
The problem was that I'm between two sizes for the pattern. I therefore made my normal assumption to make the larger size, forgetting that there are different rules for knits and wovens (you can round down for knits as they stretch). Needless to say, the top came out a bit on the large side.
The good news is that I learned how to take in seams (sides and shoulders, plus the bottom hem) as well as to round a size down for patterns using knits. So while this top isn't exactly perfect in its final fit, it fits well enough for the top's awesome style to be the most notable thing. And in the end, that's what really matters.