Boy, do I have the perfect book for you. The Exceptionally Simple Theory of Sketching : Why Professional Sketches Look Beautiful by George Hlavacs In addition, ghost your lines. This means making the motion of the line you are about to draw, without the pen touching the paper. It's like a golfer lining up their swing before hitting the ball

I can recommend the exercises from https://drawabox.com, in particular the earlier exercises.

Along with what the others have mentioned, also look at Force drawing and 'skating the page.' Also, draw big! Get some big paper and some heavy pencils or charcoal (i.e. >6B) and get loose. It's not something that'll just click overnight, it's something that will come more as you practice and things like proportion, angles and scale become unconscious habits rather than guesses and/or trying to think consciously of all these things. The biggest thing, keep practicing... but, inform your practice with good lessons so you don't just reinforce bad habits. E.g. just focus on one thing at a time (lines or angles or size), rather than trying to 'get it all right' all the time.

I struggled with this for a long time and to an extent I still do. The best way to overcome it has been Uncomfortable's tips on mark making. For line exercises, chart out 2 points, then in one motion- go from left to right / right to left, whatever's comfortable for you. The goal is to think about getting to the other point as closely as possible, without too many twists or turns. It doesn't have to be a really swift gesture, it can be slightly slower, but not too slow as that causes lines to wobble. For circles and curves, the whole 'drawing with your shoulder' principle comes into play even more. Draw big, not too small, this helps a lot. Another thing is, we often tend to just draw in circles, or lines, for practice work, but that's not the goal. In my opinion the goal is to think about it, self-correct and push yourself further. A few pages full of well thought out practice vs 20 pages of just drawing circles or getting quick lines done has a significant difference. Lastly, don't be too hard on yourself if you can't do it perfectly. The more you consciously think about it, even if it's not your practice work, maybe you're drawing for fun, you'll eventually get better on your own. Have fun!

My rough sketches can be pretty sketchy, but one thing I've noticed is that I can clean it up if I switch tools. If I want smooth lines, I'll sketch with a brush or brush pen and it forces me not to be sketchy.

Draw from your shoulder! Working on your control of the pencil is the first step towards confident linework: https://www.proko.com/course-lesson/how-to-hold-and-control-your-pencil/assignments If you see you need practice on this front I recommend going through at least lesson 1 of Draw a Box, as the exercises Uncomfortable proposes really help build the mileage for confident smooth lines. Check his lesson on markmaking where he adresses chicken scratching specifically: https://drawabox.com/lesson/1/3 He also talks about drawing from your shoulder for better line control: https://drawabox.com/lesson/1/2 I'd boil it down to consciously drawing from your shoulder at a confident speed, and practicing it until it becomes second nature (which is where Draw a Box's line exercises come into place, as they mean you'll make a lot of lines focusing on confidence and precision, which can help you build the mileage needed to apply it elsewhere). Keep this in mind every time you draw and do warmups, and it should all become easier and more unconscious the more you practice (even if it might be challenging in the beginning).

I have this problem as well. Still do a version of "chicken scratch". I think somehow it may relate to your pen resistance, if you tend to glide over the surface, the more chance you are gonna have that you are drawing very fast and repeatedly. I draw pretty firm but this means sometimes the line isn't at the place where I wanted, so I will draw multiple lines ended up messy... Try drawing big I think that helps, only my format isn't quite big enough which prevents me from doing that... I'm consciously thinking about "draw straight and long" while I put down lines... sometimes it helps.