When I was a teenager I had the privilege of learning how to ride a horse, and it was my passion. However, throughout the 10-or-so years I rode and competed, every coach who taught me and clinic I took kept coming back to the basics - how to ride a circle, how to ride a straight line, and how to balance impulsion and collection.
It's not because I sucked so badly that they had to keep teaching basics, but because at every level of riding, from the very beginner to the most advanced dressage professional, these basics are the foundation that you keep coming back to and perfecting, like an endless circle. Like the 100,000 endless circles or more I must have ridden.
I've encountered a bit of the same experience in sewing, being the beginner sewer I am: How to sew in a straight line (not to mention circles!), how to sew an accurate seam allowance, and how to keep tension in balance. It's like riding all over again, but with a needle instead of a saddle.
My first lesson is to sew an accurate 6.3mm (1/4") margin, given that everything in Europe is measured in metric. I'm learning the difference that 1mm makes. When putting together the quilt I'm working on now, I figured out that my presser foot, which I thought was 1/4", is in fact general-purpose, and 1mm off of a 1/4" (8mm to be precise).
Above are my two presser feet (hard to see with the slight angle of the photo), the aluminum one being 8mm and the plastic patchwork foot spot-on 6.3mm
I recently got a patchwork foot, who's outside edge is spot-on 6.3mm, and the difference with the general foot is barely noticeable, but will be noticeable when your quilt is finished and gnome-sized instead of king-sized.
I figured this out when the blocks which I'm working on ended up not being the same size height-wise as width-wise, as per the pattern. As I'm too lazy to rip out and re-sew all the 72 blocks now that they're finished, I'm just going to sew along the center line of the rows and make a bit of a smaller quilt than was in the pattern, and my parents, who I'm planning on gifting this quilt to, will never know the difference, unless of course they're reading this blog. (Hi Mom and Dad, and thanks for all the riding lessons!)
My quilt blocks: That 1mm of extra seam allowance ate up enough fabric to really be noticeable
Sewing in a straight line still poses a major challenge, as when I'm actually sewing straight it literally feels like it's curving, and when I feel like I'm feeding it in straight, it looks like some mountain path when it comes out. I've got to trust those feed dogs, and practice lots, I guess.
Here are some resources I've found for mastering those basics again, and again, and again:
5 Steps to Improving Piecing Accuracy on the Craftsy Blog
Sewing an Accurate Seam Allowance, a tutorial from McCall's
And this blog which is just a lot of awesomeness and fun, where he covers the basics and goes beyond too. Plus, it's just fun to see a surfer-style dude sewing.