I am learning to knit. I'm doing fine with most everything. I'm having one problem, though, that I cannot figure out. I keep increasing stitches, and I don't know how it's happening. I thought maybe there was a common mistake that you experienced knitters would recognize right away.

I am doing a simple stockinette stitch. I'll cast on 10, knit a row, purl a row, and end up with 11. Keep going, and I end up with 12. I am being VERY careful not to twist the stitches so I am knitting the back of them where there are two strands of yarn. I am knitting the front (single strand) every time. The increase always appears on the same side, i.e. after a few rows one edge is perfectly straight and the other is slanted out. The extra stitch is on the left edge when looking at the front of the right side (stockinette). In other words, it's happening at the end of the knit row or beginning of the purl row. I was doing some sample knitting last night, and counting at the end of each pass. It looks like the increase is actually happening at the beginning of my purl row. I have my work turned correctly, as far as I know.

Any ideas? I know it's kind of hard to describe this. Much easier to show someone!

My guess is that you're inadvertantly doing what is called a yarn over (YO in patterns). Here's a link to a site that discusses how to make those, so you'll recognize when you do. Don't feel bad, I used to have the same problem, but luckily, it's easy to fix.

Perhaps you'd like to join our knitting group at Yahoo, where we ask and answer such questions all the time:

http://groups.yahoo.com/group/gatheringwool/

I agree with Linda - it's a common mistake and easy to make. 

Another good resource to get quick answers to questions is Ravelry.com.  The site is beta testing, so it usually takes a couple of days to get an invitation, but it's free and I've learned a ton from the forums there.  http://www.ravelry.com/