I have always loved 3D patterns in quilts - I have made more tumbling blocks quilts than a care to admit!
Once upon a time, I decided that I wanted to make more complex patterns than the classics. Over the years that developed into a computer program that takes 3D objects, projects them onto a surface, calculates the angle of the light source, and creates a quilt pattern.
Also, keep in mind that an entire quilt doesn't have to be made with these patterns! Some are set up to be swapped in and out of classic quilt patterns, for an extra bit of "pop".
Cross-hairs: I don't know if I can call my corners cross-hairs. I mark the corners and the mid-point of every side with a line that is perpendicular to its side. That makes it easier to check that the sides line up properly.
Sewing lines: I like sewing lines. Hence I include them in the pattern.
Numbering: The piece number is written on each piece. The neighbouring piece is indicated on the mid-point line. This system makes it really easy to put everything together. I can't bring myself to use any other system any more.
Corners: My pieces are irregular sizes. Sometimes I end up with sharp corners. They can be really annoying when adding 1/4" edge, so I cut them off.