isn't any rules you have to follow if you are designing your own crafts.
If you are going by a pattern just follow the directions the best you can.
If you are just starting out, I would suggest you try a simple 12" square
pillow. Once you have master that, move upward from there.
Remember if you are designing and drawing your
own crafts patterns, then you need to add at least 1/2" to your drawing for a seam allowance. If you
don't your craft will be a lot smaller that what you drew.