Here are some cross-stitch guides because there is more than just the X
Annie’s is a good one to have bookmarked. They cover Basic Stitches: backstitch, cross-stitch, French knot, half cross, quarter cross, straight, three-quarter stitch. The best part is the short, concise video tutorials for each one.
Jean Farish is a great teacher of needlework and has a YouTube video on how and why she does the Victorian cross-stitch. That starts at 5:00.