Hi, I'm new too. First time I tried I was increasing 1 stitch every other row or more because I was excited and wanted to finish it. What I did was knit slower first and count every stitches in every row until I didn't make any more extra stitches.
But i like the idea of putting a marker. The tip of my finger was also hurting I think it has a callus already..
Thanks to all your advices too!