Nice start bro. I'm not a pro but I'd like to share a few tips.

For drawing head/portrait, you might want to learn loomis method. Very basic but can be used for any type of head. There's plenty of tutorial on YouTube. With this method you can easily draw a face even by imagination (without reference)

For shading, I recommend you to start by practicing cross hatching techniques. Quick, easy to make correction and suitable for both pencil and pen. Once you get used to it, then it'll be much easier to learn blending method.