Ditto about cotton. Wool is much, much
easier to knit because it is springy, and thus a lot more forgiving.
I had a hard time when I started too. The first thing I tried to knit was a garter stitch scarf in worsted weight yarn. My stitches were really uneven and it was taking so long that I started to think that knitting just wasn't for me. Finally, I gave up on the scarf I decided to try a smaller project -- a hat. I doubled the yarn so it would knit faster. Well, lo and behold, it was finished in no time, my stitches looked better (fatter yarn helps there -- doubling it achieved that), and I got lots of positive reinforcement as I saw my knitting actually develop into something other than a rectangle. I think I made three hats that week.
So, if I may offer my humble advice, I would recommend putting the poncho aside for a while, choosing a smaller project, and getting a light-colored bulky wool yarn and some big needles. You'll be able to see and control your stitches better, and most importantly, you'll get faster results, which will help get you excited and keep you knitting.
Another thing about uneven stitches... keep in mind that you can go always back and even out your stitches later. Just take the tip of a knitting or tapestry needle and wherever there is a loose stitch, you can tighten it up by pulling a little of the loose yarn into the stitches beside it. (I'm not sure I explained that very well, but hopefully you know what I mean.)