There are probably ten thousand books written on the subject of natural light portraiture, so you may get some great pointers at the local library.
The sun has been with us a long time (!) and the light is free, so it is a great way to start. But the direct sun is also harsh - it is a bare bulb in the face, and strong shadows where it is not. The clouds make a giant soft box, so 'high overcast' clouds will be your friend.
You will also find that the indirect light from a bright day coming in through a window or door will be your very best friend. Particularly when you learn to sit your subjects at the 'edge' of the fall-off inside the room. It can be the best of all light. Of course, you are also going to find a cartload of challenges with colour temperatures of natural and artificial light and how they affect colour film. Not so, happily, with black and white.
You will also soon find that just one little portable reflector - maybe cl&ed on a tripod - will be a great balance for you on the 'dark side'. (Think Darth Vader). Then, you'll wonder about flash fill. (And then, two assistants, an RV, generators, full studio light set up, the snoot, the barn-door, gobos, blah blah blah.)
Hint: natural light is good! Bare necessities free you up.
As I said at the top, there is plenty to read! You have a new camera and you will first need to be comfortable with it, of course. And then, I say, jump in. Grab a roll of BW, get a sitter near an open window or doorway, find the edge of the light, place the sitter at the best angle to 'work' the face (soft shadow on one side is your friend), take an incident light meter reading of the face, think, compose, and shoot! Make notes. Remember the conditions outside. By the way, you can also do this outside, under an porch roof, an overhang etc.
I quickly searched and found many books at Amaz*n, with "previews". Have a look. You'll get a few quick clues.
That's my two cents. There will be many more at this forum who qualify to give you fifty cents worth, or even a dollar's worth.
Look forward to seeing a few portraits up here !