Using inspiration - catalogs, photos, drawings, advertisements, and other image and writing sources (stories, myths, legends, etc.) can be a great inspiration. If you have no idea how to get inspiration, I've written a blog article that can help.
Padding your own sketches or other images to develop your own final image step by step can be very helpful.
Line remains line - If you draw with a pencil, you can erase wrong lines again. But if you draw with a pen or other pens, where the lines are not close, you draw much more thoughtful and makes sure that the lines are set as correct as possible. Nevertheless, one will have wrong lines, so it is advisable to make only sketches or drawing exercises in the way.
Work Materials - An oblique table, a lightbox to drop the file, a tray for the pictures, a dust brush to clean eraser remnants etc. - there are many tools that make drawing and managing the pictures easier. It is important that you always sit well and comfortably and enough light is available.
Practice makes perfect - You can still be so gifted, you do not practice regularly and you set yourself more and more new standards and goals, then you can hardly improve. Still, it should always be fun. If you have no fun, the work can only go in the pants.
Correction - If you can not recognize any "mistakes" or areas that require improvement in the picture, you can submit it to an independent person and ask them for their opinion. It's mostly like self-written texts where you have to look for mistakes; You overlook them again and again, so you can read them correction - images can therefore be seen correction.
Get criticism - Ask friends or relatives to look at your pictures and voice their opinions. Do not take criticism personally. No friend wants to deny or downgrade your skills but honestly tell you where there is room for improvement.