To gauge or not to gauge... that is the question

So erm, the more I read about crochet (ah oui, je ne vous ai pas dit, mais parfois, je vais écrire en anglais aussi!), the more I wonder how I can get it right, since as I don't bother with gauge... I know, this is bad. Really bad?!

I seem to be getting away with it so far.

But it is necessary, isn't it?

My problem is that if my gauge does not correspond to that of the pattern: WHAT DO I DO?????

I tend to take the information given on the yarn label and use that as a base. Of course, when you make a shawl or a scarf, it's not too much of a problem. Plus, you can easily alter the length or width from the start or at the end.

But things could have gone horribly wrong when I made the Saturn cardigan (Interweave). So how do you manage with your gauge? Any useful tip will be welcome!

Thanks! :-)