Woodworking

Measure twice cut once is rookie numbers. Measure 10 times, cut a test piece 5 times, measure twice after each, then do your real cut.

This is a bit of an exaggeration, but you get the idea.

Also, measure after each operation to check your work as you go so you can spot mistakes as early as possible. This includes checking for square, doing test fits, and all manner of sanity checks to ensure that your operations are achieving the desired results before you repeat them on other pieces or move on to do more work on those same pieces that may already be ruined or need fixing.

For glue up, always always always dry fit first. Then plan ahead. Put all your clamps on and have them adjusted before you add glue. Once the glue is on the time is short and you need to have everything ready and waiting.

If you use a table saw, take it seriously. Always use your riving knife when possible, be mindful of the control you have over the pieces, use push sticks and sleds and jigs to improve stability and safety, always wear ppe. Check that your blade is aligned to your miter slots and your fence. Having a slight relief angle on your fence can be good, but never have it canted towards the blade. That can be dangerous. Also make a crosscut sled, they’re amazing.

Beware of dust. It causes cancer and it lingers in the air. Wear a respirator and use ventilation when possible.

Make or buy a workbench with a vise and some hold down capabilities. Being able to hold your work easily is a huge benefit.

If you are looking to improve your accuracy and precision, buy a nice hand plane and learn how set it up, sharpen it, and how to use it. They are absolute game changers. Also make or buy a shooting board for it. Also, buy a machinist’s square, a set of feeler gauges, and a nice 36in aluminum straight edge and learn to use them.

Etc

Obviously that’s a lot, and a lot of it it depends on what you’re actually trying to do, but those are all things that have helped me a lot in my journey towards making furniture, picture frames, cutting boards, etc