Hi Liam! Thanks for the kind words, I really appreciate them. And you can call me Charlie. 
Let me be honest, I have had drawing tablets for quite a while now, and have been drawing since I was a kid, but never took it quite seriously. You know, life gets in the way and stuff. 
. I took drawing seriously about four years ago when I jumped into Graphic Design, but did not stick to a structured routine for digital art specifically.
Thanks for the comment about my circles, still I find I could improve a lot, lot, lot more.
Let me see if I can help a little. I posted this on your thread as well, but maybe someone else might find it useful.
If your using Photoshop a tip I like to use is to rotate the Canvas to find the right angle for my strokes. You can rotate the Canvas with R, draw, and then hit Escape to go back to the default. Try finding the angles you feel more comfortable, just like you would in a sheet of paper. It takes a little practice but is very rewarding. Also, I use shoulder and arm movements. I try to restrict wrist movements for when I'm detailing.
For straighter lines and circles I like to use 'ghosted lines' combined with rotating the canvas. From what I’ve gathered about 'ghosted lines' is to try to find the starting and ending points, practice the stroke without marking the line and then, when you feel confident, draw the line in a single and fast move to avoid scratching or wobbly lines. Again it takes a bit of practice and I’m by no means an expert. I’m just starting
Some people find the Drawabox exercises very useful, but you should know that his method applies on traditional media. I’m sure you can translate some of the exercises to digital media as well. Here’s a link: https://www.youtube.com/watch?v=9708PBUvCQ0&list=PLA7yj0dxiUGv7k8ohEt15EtMz9PTckNXw
Sorry about the long answer. I hope this helps, let me know if I can help you even further.
Have a great weekend Liam. ¡Pura Vida!
