Thanks for the nice comments! I'm really enjoying stitching this one.
Sally, I stitch with a hoop, but I recently found a tutorial online by Mary Corbet and discovered I wasn't properly taught how to set up the fabric in my hoop

I haven't been adjusting the fabric or tightening the screw enough. Hopefully being mindful of that will help.
Cristaltipps, thank you for the link to the continental tent stitch--it has very clear instructions! I'll have to remember that for future projects. Since this one is a kit, I'm afraid I could run out of thread because it looks like you'd be using more thread along the back. The skew isn't too bad yet--but I do have a completed one that will probably never be stretched straight.
Carole, I used to really dread the backstitch when I left it to the end. When there are a lot of similar colors, it's hard for me to figure out where to put the backstitch. Someone on this message board posted about doing it as they went along, and I just had to try it. Yay for having a place to get great ideas from fellow stitchers!