Machine basics
Machine basics: technique guides for US sewists.

I poke through every pattern and product so you only get the best.
– Pinny
How to change a sewing machine needle
Change the needle about every 8 hours of sewing (Schmetz) or at the start of each project: loosen the clamp, drop the old one out, push the new one fully up with the flat side to the back, and tighten.
Choosing the right sewing machine needle
Universal, ballpoint, jersey, stretch, denim, microtex: match the needle type to the fabric and the size to its weight. A fresh needle fixes more problems than you would think.
Loops, knots and puckers: fixing thread tension
Most "tension problems" are really threading problems. Rethread first, then adjust the top tension one number at a time.
How to sew in a straight line
Watch the seam guide, not the needle. Line the fabric edge up with a mark on the needle plate and let the machine feed the fabric while your hands just guide it.
How to thread a sewing machine and wind a bobbin
The two jobs every sewist does first. Your manual is the final word for your model, but almost every home machine follows the same pattern.
What a walking foot does and when to use it
A walking foot feeds the top layer at the same rate as the bottom one. Use it for quilts, thick layers, knits, checks and stripes you need to match.