The waxing and ironing of your hand sewing thread is to create a perfectly smooth thread and eliminate any small imperfections in the thread. Regular machine thread is very 'fuzzy' if looked at under a magnifying glass and this that can also cause your thread to give you problems such as knotting up and twisting when sewing. The more expensive the thread, the smoother it will be. Thread has a twist! When you are hand sewing, your thread will knot and kink less if you work with the twist rather than against it. The twist usually runs in the direction from the loose end of the spooled thread toward the spool. So when sewing by hand, thread the needle with the end of the thread that first comes off the spool. If you have cut a length of thread and are unsure of the twist's direction, look at each end. Thread the end that's pointed like a flower bud and knot the end that flares open.
If you have chosen the option of finishing your raw hem edges by hand, the trick to making very narrow rolled hems is to lay your needle along the raw edge of the fabric and with your fingers roll the fabric tightly around the needle to get it started. Start by anchoring your single knotted end about 1/4" down the side in the seam allowance, taking a single back stitch when you get to the rolled hem edge and going from there. I tried to take a photo of this step, but have yet to get a closeup that is clear enough to help. I will keep trying.
As you are sewing the rolled edge, pick up a single thread of the fabric and hide the length of your stitch inside the 'roll' of the hem to create a nearly invisible finish.