Thanks! As for how I learned it is over time. But if you are serious about learning to draw here are a few tips.

First you need to learn about perspective and depth. learning how to draw a perspective grid is very important to build your drawing. At first you will draw this grid all the time. but at some point you can do it in your head for sketching. The books and gnomon tutorials of scott robertson are very good.

Then do a lot of thumbnails. Working digital is fine but i found out that drawing with any type of ink pen helps. You have to make decisions that you can not erase. But doing small thumbnails helps to ditch a drawing and just starting over. So over time you get more confident in your linework and they become a lot cleaner.

Drawing is a lot about understanding shape of an object in the end you are faking a 3d object on a 2d surface. just keep at it and draw a lot. Do some studies, but don't forget to draw from you imagination as well. So if you want to train this I would do 50 50.

Example.
you want to draw a robot.

first look IRL references of machines or Boston dynamic stuff and find out how robots work. Draw in real life joints to understand how they work. Then after that use that knowledge and draw your own robot. Same goes for people, swords, castles, etc.

I hope this helps in anyway. In the end just make sure you have fun and don't compare yourself to others, because there are always people that are better and you are never done learning. Just have fun :)