1) Back up**
2) Be explicit***
* You remember the two things meme, right? I can't be bothered to find the web page but I'm sure if you Google for "the two things" you'll get it. Anyway, these are the two things which seem to be surfacing as the things to remember. YMMV
** This one is mostly a computer context thing, obviously (although I do have copies of some important records, for example). These days, space is cheap (OK, that only applies to computers!) and time isn't. If you find yourself thinking "I wonder if it's worth backing up before I do this" then the answer is yes. It's always yes. There is functionally no cost to backing up and mostly it doesn't take that long. Check into source control often. Work on a working copy of your document so you can save your changes without having to necessarily keep them (or use source control, of course). Back up the database before you do it. Give yourself a safty net.
*** More generally applicable. I thought about this earlier while thinking about money in relationships. One of the reasons Alex and I don't argue about money is that we have sat down and explicitly addressed it. What's mine, what's his. How much we should contribute to various costs. What the expectations are. We did it pretty early on, we did it again when we moved in, we did it when we bought the house. We've ended up with quite a formal arrangement, perhaps, but I don't think that's a bad thing. And that extends across every part of our relationship. I think that the reason we fight so very rarely is that we try to be upfront about everything and its a principle I've since tried to apply in all my relationships.
The motto is "If you don't tell them, they won't know". You just can't rely on people to pick up the subtle signs you think you're broadcasting so if they're bugging you, say something. Do it politely, and be diplomatic but be honest. Otherwise, nothing will change and you'll end up nursing resentment or fear and its not worth it. Its often scary to say it because sometimes you haven't really faced your expectations either and no-one wants to come off selfish but if you find you genuinely can't abandon something then be prepared to give and take elsewhere and give it a try.
Anyway, I'll shut up now.