Leah Day's videos are wonderful.
So are Heather Thomas's. She has a 4 part video for beginner FMQ-er's that covers some tips that Leah Day does not. Here's a link to the first part:
https://www.youtube.com/watch?v=LLWFmOForjU
I like Heather Thomas because she will actually show examples of her quilting & explain that she couldn't do X, Y & Z until she had been quilting for 20 years.
Make sure you drop/cover your feed dogs, set your stitch length to "0", use the same thread in the top & bobbin (ideally 100% cotton -- it's the easiest to work with for beginners -- and the same color), and do whatever you can to give yourself a decent sized sewing surface ... a machine set into a sewing cabinet is ideal; next best would be an extension table; after that, do what I have done & try to make yourself an extension table by finding boxes the same height as your machine & masking tape them to the bed of your machine.
Then, pick a very basic pattern to start out with -- a meander or loopy pattern. There are lots of beautiful patterns out there, but it takes years to learn how to do those. If you really have your heart set on a complicated pattern, you probably want to either hire a long armer or see if someone in your guild will help you out in trade or for a nominal amount. I've heard several different quilt teachers say you need to make 3 ugly quilts before you get the hang of FMQ (I think Leah Day suggests that it's only your first one). In any case, if you have your heart set on quilting it yourself, I think you're probably going to want to make some charity quilts or quilts to give to family/friend's children first.
But once you're seeing loops. Stop. Make sure you are using decent thread (not your grandmother's old thread that someone found in a box up in the attic) that is 100% cotton. Then, make sure you are threading your machine properly. I know with my machine, if I make a mistake with the threading or if the thread snaps, it says to cut it up by the spool & pull the thread out by the needle, then re-thread from scratch. Maybe check to see what your manual says.
Like others said, make sure you have a darning/FM foot on. If you can set your machine to the needle-down position that will help. And if you can reduce the sewing speed with a button/slide, set it to the lowest setting. And I strongly recommend marking your quilt because it's generally easier to follow a drawn line than to figure out how to move your hands and figure out where you're going to go next all at the same time.
It all just takes lots of practice. I made a couple quilt sandwiches to get my machine settings sorted out the first time I FMQ'ed and then I made some changing pads as practice. After that, I picked a white thread in a 50wt/2 ply by Aurifil that would blend in with the background so my mistakes would be barely noticeable. And I ended up going with a 1" meander. I had wanted to do smaller, but couldn't consistently produce a decent stitch and a simple pattern that's well-executed will always look better than a complicated pattern that is poorly executed. It took me 50 hours of practice + quilting time to finish my 1 year old niece's 38x52" quilt. I ripped out a few stitch lines on the actual quilt and re-did them because the stitches didn't form properly (I went too fast) and in one of the corner I got loopy threads. But mostly, I left all my mistakes in. I don't regret doing that for one minute. It shows my progress. In fact, by the time I reached the borders, I was confident enough to create my own design of a leafy vine & quilt it in the border. It turned out beautiful (in my opinion).
On the quilt I'm just finishing, I want to add a feather in the border. I've never done feathers before, though, so it's probably going to be 7-8 hours of practice just to get that one feather shape decent enough that it somewhat resembles a feather. But then I will have learned another shape to add to my repertoire. It's all about starting with the basics & building up from there. We wouldn't expect someone who didn't know how to count to learn to do advanced calculus by the end of the week. We can't expect a similar miracle with our quilting. You'll get there. Just keep working at it!
