I learned from books and videos too. :)
Here are some things that I had to learn the hard way:
A consistent 1/4" seam is a lot harder than it looks. Murphy's law - if you've hit it perfectly, you will have forgotten to re-set the stitch length from your basting project and you'll have 6 stitches per inch in that seam. Conversely, if it's far enough off 1/4" that you need to remove the seam, you will have sewn it at 30 stitches per inch. :mrgreen:
Keep little scraps of quilting cottons on your sewing table and check your stitching top and bottom every time you change bobbins, needles or thread. Adjust the bobbin tension for the thread that's in it and balance the needle tension with the bobbin tension. The one time you forget to check your stitching, your needle side will be making beautiful stitches and the bobbin thread will be pulled tight - and therefore, useless - on the underside. Naturally, you will have sewn several miles of this type of seam. ;)
Change your needle every six or eight hours of sewing, or when the needle starts making a little popping sound as it enters the fabric.
Don't collect all medium-value, medium-scale prints. Your quilt needs contrast in light and texture to show off the design and your constantly improving piecing skills.
Stitching in the ditch is hard! If you sew a shallow zig-zag or wavy or serpentine stitch in the general vicinity of the ditch, you won't be pulling your hair out trying to keep the needle IN the ditch and not jumping off to one side and then the other. This can help you disguise little oopsies in the piecing, too - stitch in the ditch emphasizes those oopsies.
Learn how to "ootch and scootch" or "fudge" seams - when you go to sew two blocks together and one is 1/16" longer than the other, put the bottom block on the bottom, hold the ends aligned with each other and keep a little tension on the fabrics as you sew them together.
When you're sewing rows, pin the intersections on the side that will go under the needle first. The top block will be a scootch larger sometimes and the bottom block will be a scootch larger at other times. Only pin at the intersections, where you want the blocks to line up. In between intersections, hold the blocks aligned at the pins and put a little tension on them to ease the very slight extra fullness into the shorter block.
Breathe. ;) Have fun with it - learning is a great joy and I'm glad that I'm still doing a lot of it every day!