How do I tell my gauge?

Obviously I’m a new knitter (about a month).
I’ve made a few little things I’ve found online, but each time I’ve had to make it, make my notes about how much smaller I need it to be, then rip it apart and remake it.
I’ve tried figureing out my gauge, but, to be honest, I just don’t know what I should be counting.
17 sts = 4’’ is what the hat I want to make says. Do I count each bump seperately? Does an underbump and overbump count as one stitch?

I’m usually pretty good at figuring stuff out on my own, but I don’t want to have to go through my knitting career makeing something just to have to do it all over.
(By the way, I’m a visual learner so any pic tips would be most helpful.)

Thanks!

Here is a very thorough article on swatching/gauge, with lots of pictures :thumbsup:

http://knitty.com/ISSUEspring03/FEATswatchout.html

[color=magenta]Maybe this will help. I put a line on either side of one stitch.[/color]

Thank you both so much! I really appreciate the help. :slight_smile: