The star stitch is easier than it looks - I added a link to a tutorial on how to make the star stitch (you can vary from there) on my pattern link for reference - once you get “stars” in your eyes - there’s no turning back!

I personally like the variegated/ombre yarn best for the star-stitch - but solid colors work great too.

Any size yarn will do - play around with different sizes of hooks to get the feel you want - I have used J K and even L to make a looser star stitch - really cool!