Welcome aboard, theonixie!

That looks absolutely magical! Gorgeous light in those clouds!

Yes, portraits are particularly challenging most of the time, but there are many things to study before one has to jump on portraits. The most important thing is to get a feel for the paint, gain control over certain actions and how to achieve various effects, materials and even shapes.
Then there is how you might wish to approach more specific forms or accurate depictions such as portraits. It's great to use a top layer for making a "pencil" sketch and then have a bottom layer where you actually paint. But, yeah, I'd first spend time exploring the feel and figure out your techniques.
Especially for portraits I'd work with low or even no fluidity, depending on where you're at in the process. No fluidity is perfect for sketching, of course. 10% or less are good to get smooth, dense strokes.
Also I recommend to fill your paint layer first, because it's like priming the canvas and everything feels more familiar and is more dense that way right away. And don't forget to look at the "BUILD UP" parameter or [b] to bring up the floating widget of it. In any more accurate painting you may end up preferring 0% build up, if there already is enough paint on the canvas. But there are many tricks and ways to go about it nicely.
I'm definitely already looking forward to more from you, that's for sure!
