The pictures should speak for themselves for the most part.
Yes, you could just make an "X", but I tend to mess that up, so doing each line individually is easier for me.
Don't worry too much about how smooth things are. A good top coat will conceal any lumpies.
The above picture is just to show you how I avoid having a large ball of polish on the end of my brush. Dip and drag.
I used Sally Hansen Wet Cement for the base color, white Stripe Rite (which is acrylic paint, not polish) and China Glaze Liquid Leather for the "stitching." Don't hesitate to leave a comment or message me if you have any question!