Gosh, who am I to be giving tips on gauge? except that I do knit swatches before I start a project, and a good thing too because I vary widely between spot on and waaaay too loose. In fact I've begun to invest in additional small-size needles to cover myself for yarns that really don't work with a looser tension. But that's a subject for another day.
Yes, gauge. Somewhere, recently, I read a really clever idea for knitting swatches in perfect squares, including any special cables or stitches that appear in the pattern, and then using them later as pockets in a purse or on a sweater, or as squares for a quilt. Isn't that brilliant? Don't you think it has maximum cuteness potential?
Here's what I do with gauge swatches: I knit them and measure them and record my findings wherever it seems most sensible at the time, and then I rip them out and use them in the project. Who has enough yarn for gauge swatches that have to go begging?
Anyway, here are my tips. Knit enough of a swatch to give you some leeway between, say, 3 inches and 5, and don't hesitate to measure in metric if that's going to give you a more accurate count. And take the swatch off the needles before you measure.
(Seriously - it's amazing how much more relaxed stitches are when you let them off the needles, like they're all freaked out when they're on there wondering what exciting thing is going to happen next, even if they aren't going to have much to do with it because they're 12 rows down already and getting farther away all the time.)
And with that, I will get back to my editing assignment so I can get back to knitting my lovely green hat.