I taught myself to quilt years ago. I learned a couple of things. Choose a simple pattern first. Don't be in a hurry to finish it. Take a little time each day, even if it is only to stitch one seam, and eventually it will get done. Do a "tv" size quilt first. I usually make them 5x7 feet. It will be easier to handle and it will get done quickly. Having a finished first quilt will make you happy and want to make more. A too difficult quilt or too big quilt can be discouraging at first.
Don't worry about being perfect. It's no big deal if you cut off the points of stars. The size of the block needs to be the size your pattern calls for. The seams inside the block really don't have to match perfectly. Eventually, you'll learn how to get better at matching seams up.
Don't buy too many doodads right away. Scissors, rotary cutter, cutting mat, a 6x12in ruler will do. You'll need two kinds of thread if you are going to hand quilt. Sewing machine thread and quilting thread for hand quilting. If you are going to quilt it on the machine, you just need sewing machine thread. For piecing, just buy one spool of a neutral color. Everyone has their favorite neutral color. I just use a lightish beige. After you finish your first quilt, you'll know what doodad you would really want and use. I have a zillion doodads that I never use.
Adding borders is an easy way to enlarge a quilt. If you get tired of the block/fabric that you have chosen, or you are just not happy with the quilt, just add a couple of borders and you are done.
Consider tying your first quilt. You will get the quilt done faster. The type of bat is important. If you tie it, I'd suggest a 5oz polyester bat. It will give loft to the quilt and you won't have to make so many ties.
Ask for help along the way. It's better to have advice when you get stuck. There are always more than one way to construct a quilt. You'll eventually find what works best for you. Post on this Board and you'll always get a lot of help fast!
Finally, try to create a mind set that doesn't see doing the different steps of quilting as fun/awful or love/hate. Tell you brain to think of fixing mistakes as simply a part of quilt. Ripping out seams is just a part of quilting. If you hate it, you'll not want to do it and be upset that you made a mistake and have to rip it out. Instead, think "this is part of quilting and I love quilting." Once your mind thinks this way, you won't be so upset, angry, or frustrated that you made a mistake. It's a lot more fun if you don't hate having to do something.