If you don't know the difference between volts and watts you should not mess with electricity. If you don't know which operational system your computer have you should not try to fix it. If your knowledge about how a car works is by putting gasoline on it, you should not try to repair the clutch by yourself. If you need to ask the guy at the counter how to do something is a clear sigh you should NOT do it.
Seriously, half of my clients have no idea what they are doing, but they know that they will not spend a single cent with specialized help or at least doing some kind of class before messing with things they have no idea how it works. In fact, sometimes I wish that clients should be forced to do class on the subject a store sell before even be allowed to set foot in it.
And that is not counting the guys who apparently have nothing better to do than pest the attendants! Really, if you are bored, go see a movie, not bother store clerks!