Well, your st marker should help you figure out which is the last st and first st. PM after you cast-on.
When I knit with DPNs, it helps me to use a throw pillow from the couch. I sit it in my lap and knit on top of that. It helps me to keep my DPNs flat so that I can knit them easier.
Also, once you get past those first few rows, it gets easier.