Paul,
The easiest way to have miscuts using a small blade is to use speed that is too fast. Cut down on speed and follow pattern lines carefully. When you are done, inspect everything with care. You can use a larger blade to smooth out curves and corners. Then use the small blade again to get what you want. Be careful to keep the curves or arcs as consistent in their sweep as you can, especially if curves come together to a point. I can't overemphasize enough how important it is to back into a sharp point or corner (not using the saw edge of the blade) and cleaning up with the saw edge of the blade. You may have to cut into the point again to make it sharp. I hope this helps and was clear in my explanation.
Also, when cutting transparent acrylic, you may see a white sheen on the cut edges. I put the finished piece in warm water for a few minutes and then buffed with a soft cloth. Cleaned it up somewhat. If anybody knows a good way to remove that sheen, I would really like to know how.