I do my own pedicures most of the time and I can say that it gets easier and you get better at it over time. You also start to develop techniques - like making sure there's not too much polish on the brush so that you can paint your nail better and you end up finding the most comfortable position to sit in to paint your nails. Example - I have to paint my nails while sitting on the couch and with my foot propped up on the coffee table, I can't do it anywhere else.
So, in the case of painting your own toenails, "practice makes perfect" is really true!