That's a good point--being aware that, the less you know about the topic, the less equipped you are to judge the difficulty of the change or the value of the favor.

Luckily, I know just little enough about computers that when my famliy asks me for help (which isn't too often--my parents have been using computers longer than I have), I can often just honestly say "I don't know, look it up." ;) (This worked even better when I was using Linux as a desktop OS and was way out of date with Windows and its common programs.)