I just started knitting again a few weeks ago and have been on this website for most of my waking days!
One thing I haven't seen mentioned though, that I sorta figured out while teaching myself to use DPNs (as you are!) is that to avoid ladders when you switch out needles, instead of making the "breaks" at the same stitch every round, I add about 3 or 4 stitches from the next needle (the one with full stitches on it, not the one that you just freed up) onto the old needle and then take the bare needle and start working on that. Then when I'm done transferring from the one needle, I add a few more stitches from the next needle. Does that make sense at all? Too many vague demonstrative pronouns maybe?
I'll include pictures if I need to.
But it sorta keeps the loose knit rotating so it evens out. Or just make that join real tight.