Like you, I'd been sewing for years but had never done quiltmaking. I am self taught, which is kind of how I approach everything. I didn't khow what I didn't know, at first, and have learned a lot, both here and from reading and online. I suggest you Google quiltmaking, quilt cutting, piecing, all things quilt related, and watch the videos. Also, buy a book or two of basics, with photos that show cutting fabric. Get your 6x24 ruler and maybe a 12 inch square, too, to start, and just start cutting.....carefully. (When if first began, I loved the cutting process. Now, not so much
. My first was a simple 9 patch, throw size, made without a pattern, just made enough blocks to the size I wanted. I read up on sashing and backing and finally borders (I brought the back to the front as a border on that first one and hand sewed it).
Go slowly and carefully and have fun!