Adding sts. at end of row?

Hello friends, I am working on a child’s raglan sweater “ king cole pattern #5257” the problem I have is that it asks to cast on sts. at the end and beginning of the rows, and I am doing that but it creates a very sloppy edge which I feel it will be a problem when joining all the pieces. Never seen a raglan worked that way. Any suggestions how I can make those cast on sts to look neater???

Instead of casting on do an increase one stitch in from the edge.

Thank you for your prompt reply, my issue is that it is not just one stitch, it start with casting on 3, then casting on 4 , so I was doing cable cast on’s but it leaves a very sloppy edge☹️