LOL, leaving the game on. My mom used to get pissed off when I did that, because it would "wear out" the game. Did anyone else's mom used to say that? Hey, it works for tapes and records.
A key difference between old-school and new games is that old games were basically a test of skill, and guides can't really help if you suck at the game. I had the FF7 Bradygames (the official guide, whoever did it) strategy guide, which actually I think the first RPG that had a guide of such scale, and it tells you everything about it.
When the internet was fairly new I'd go through the Sierra games with a walkthrough to see what I could see. This is an idiotic thing to do but thankfully I've forgotten almost all of those games.