Another thing with holes...when I was just beginning, I did accidental yarnovers a lot because of how I was moving my yarn back and forth. Check to make sure you're not accidentally looping the working yarn over the right needle before starting the next stitch. What happens is you'll knit into that and make an extra stitch and a hole when you do the next row. (It's an actual stitch used to make buttonholes or lace patterns....but it looks bad when you don't mean to do it!!)
I agree that if you count your stitches after each row, you'll catch these things much sooner and be able to fix them. That's how I finally learned to pay better attention and be more consistent.