* Squaring up your blocks after making them inevitably means that you will have to rip out seams and re-sew them. As one of my classmates said, "I wish I'd paid more attention while making these things, it would have made this part easier." No kidding. Watch out for those quarter inch seams...they'll gettcha!
* Sew around the edge of your quilt top (quarter inch from the edge, running stitch -- nothing fancy) once it's all pieced and before you make your quilt sandwich. I can't say I really understand this part but apparently it has something to do with preventing your quilt top from becoming not-square. (I have a feeling advanced quilters are reading this and laughing -- that's OK).
* Binding strips are sewn together on an angle because it prevents bunching at the seams when you roll your binding and sew to to your quilt. My guess is a diagonal seam also distributes tension a little better to that seam, so your binding doesn't pop open inadvertently.
* When taking a quilting class at a store ALWAYS ask what the total cost of the class is, and if it's OK to bring your own fabric and what supplies will be supplied as part of the cost of the class. The cost of my class has doubled due to unnecessary supply purchases, and my inability/reluctance to ask these questions and/or just assuming that it was all inclusive.
* Color choices and fabric pattern picking: is this generational or learned? There are some wonky color/fabric choices in my class.