I'm curious why the need to use manual mode? Camera A or S mode will be much more satisfactory (and more usual mainstream), and will still let you control the aperture (or shutter speed) condition you deem best for the current situation. Unless there is some specific reason (which I can't imagine
), I think camera M mode would be the hardest possible way, for no good reason... esp for a newcomer. Just one opinion, but it is your camera of course.
A 30mm focal length would be considered a "normal" view, normal for our eyes, and suitable and normal for many average situations. Indoors, where space behind us is short, sometimes a little wider is necessary to include all of the view. For a portrait, always try to stand slightly back, like 6 or 7 feet, and zoom in all you want - so a little longer, towards the 55mm end of the lens you have. It really depends on the view you want to capture - maybe a little longer for tight head and shoulder cases, but shorter of course would be instead necessary for full length or group shots. But the right focal length in any situation is the one that shows the view you want to capture.