Threading it up seems complicated at first, but once you have done it a few times, you'll think nothing of it. If DH is "handy" with machinery, enlist his aid the first time round (but not if he is all thumbs with technology!)
When you think you have mastered threading up, get a scrap of material (an old pillow-slip?) and practice some straight rows of stitching, trying out the different stitches, tensions and so on. You will be sewing on two layers of fabric for your pinafore, so use double material.
My memory of starting out with a sewing machine is that the biggest hazard was that when I started to sew, the thread always leapt out of the needle with the first stitch and I had to rethread it. One machine I had would then tangle the end of the threads and refuse to do any more until that was sorted out - so make sure you leave at least 6 inch tails of top thread and under thread, tidied to the back out of the way of the stitching.