Originally Posted by AmishElectricCo
One thing you definitely don't want to go cheap on: layout tools. Squares, rules, etc.
Nothing is more frustrating than investing time and money in a project, only to have a joint not line up correctly or be out of square because your tools aren't accurate. A good 12" combination square will cost $75 or more - but it's well worth it.
It sounds like you've had bad experiences with squares.
I may have just been lucky. I have two combination squares - both the typical Stanley ones. One is a bit off, which for woodworking is absolutely not okay for the reasons you mention. The other one, however, is dead on. I haven't measured it with any precision tools, but it passes the line-flip-line test every time I try.
Scott Wadsworth (The Essential Craftsman) states:
"...the key to being a good hand is to understand allowable tollerances. Sometimes if you're working to plus/minus 1/64", you're working way too sloppy. Sometimes, if you're working to plus/minus 2 feet, you're cutting it way too fine." - https://youtu.be/jDfpl1_I904?t=889
If you do a lot of joinery (whether that's fancy stuff or pocket holes) tool setup tolerances ought to be tight so that things naturally square themselves up. So, for the beginning woodworkers, point is: check squareness of tools. Personally I wouldn't jump to a $75 square until I tested a couple dozen $10 ones. If not square, you can return it. It's a square.
Also note: A deck of cards is wildly accurately square, and verifiably so: Take a card, flip it backwards, put it in the middle of the deck, and see if you can pick it out from the rest of the deck. Same would go for cardstock (haven't tested it, but the same test would apply).
Also also note: I think beginners ought to learn how to square/align/parallel their tools properly without squares before they go out and think a $75 square will fix their problems. William NG's video on how to square up a table saw sled fence is an example of that. So, as this thread is for beginning woodworkers, $75 will likely save you some hassle, but the underlying point AmishElectricCo is making is worth repeating: properly square tools will save you more hassle than you realize.