If you have an even number of stitches, you would start every row with a knit. But you may have inadvertently added a stitch, so count them to see if it's the same you started with.
Learn what your knits and purls look like. So when you get to the next row, if a stitch looks like a purl, you purl it, or if it looks like a knit, you knit it.
sue- knitting heretic