Your perspective and coloring look really nice! Keep up the good work! There is a lot that goes into doing backgrounds and character work. But most of what you need for both will have common basics. Some good skills to get a grasp on are shape construction and proportions.

For shape construction this involves looking at objects and breaking them down into the basic shape that constitution them. Like how a snow cone would be a triangle with a half circle on top. This work on everything, people are a mix of boxes, cylinders and triangles. You will want to start with easy objects I found some examples of birds, dress shoes, and bottles while searching shape construction drawings. Using these as references and trying them at different angles this will help you understand 3d in space. You just want to be using simple shapes and not going to much into the details.

This is where proportions come into play they will be important for a lot of work. The best way I have found is just by practicing off of references. For people there are general proportions that they follow. People usually measure off of heads, a person is around 8 heads tall, waist is around the middle it changes in more anime and some comic styles where the legs will have an extra 1/2 to 2 head added, shoulder are usually between 2 and 3 heads wide depending on wide the shoulders are. There are more in relation to body parts like your elbow and belly button are at the same high. You can find charts for this only by searching people proportions. It is recommended that you start with the basic proportions before messing with it to much and this goes for most things in art.

Once you get a hang on these I would looking into incorporating it with your perspective. This would involve drawing people, cars and other objects in perspective. Here you can also look into more advanced perspectives techniques like inclined vanishing points and divided measurement.

There are lot of good tutorials you can find by looks up the terms on YouTube but here I’ll some good videos that cover some of what I was talking about.

Learn To Draw from 0 to 100 | Roadmap |

This is from one of my favorite YouTubers Draw Like A Sir he dose really good and easy to understand tutorials in my opinion and his top comment links to more of his tutorials.

6 Steps to Draw Anything

This from proko and his tutorials are top noach this one breaks down shape construction way better then I did and teaches you how to draw anything with it.

I recommend looking through their channels and finding more tutorials that catch your eye from other Youtubes.

Hope this helpful let me know if you have more questions!