Crocheted Blanket Question?

I've been crocheting for over 40 years and the only thing I make are afghans. (Let's just say that every family member has two or three of my blankets!) Every row-by-row type of afghan that I finish before making an edging looks slightly 'wavy.' Even the granny square kinds look like they need tightening up. It's just the way crocheting looks until you put on the edging. I always start by doing a single crochet stitch all around the perimeter; sometimes once around, sometimes two or three times around, depending on my design. It evens out the 'wavy' look, and it makes it easier to add a lacy or shell edging to finish off the afghan. As long as you're sure you're not adding or subtracting stitches on any rows, I'm sure once you add your edge, it'll look alot better. You're tension will improve once you get a couple of more projects under your belt. All it takes is a little more practice.