I had sewed for years before I started quiltmaking and like you, learned by reading and from online sites.
So, not knowing how much general sewing experience you have, my advice, on this first one, is to go slow, press don't iron seams, make sure they match when sewing them together, don't hesitate to rip out if they don't, try to be patient, and enjoy the process and, finally, your finished product!
Welcome to a very addictive but wholly satisfying hobby! And to this board!