If you only do one thing before starting a DIY project, do this

[Puma37]

Skip the tool shopping, skip researching every possible technique, and do the one thing that actually prevents most beginner disasters, measure and mark your exact space or material twice before making a single cut. The overwhelming majority of ruined materials and failed first attempts trace back to one wrong measurement made once and trusted without ever double checking it

This single habit costs nothing beyond a few extra minutes, and it catches the kind of small error that otherwise doesn't reveal itself until you're already partway through and the mistake has become expensive or impossible to fully undo

Everything else, the right tools, the perfect technique, matters far less if the fundamental measurement underneath the whole project was wrong from the very first step. Curious whether people have a story where skipping this exact step caused a real project to go sideways