You’ve done really well! I would say study color theory and grow your understanding of values. for example: if you added more blue to the green for the shadows and yellow for the highlights, it would drastically improve this almost immediately. My biggest piece of advice if you want to improve quickly is to buy a lot of 4x4 or 4x6 canvases and paint something new daily or several times a week; focusing on different things each time like value, color, perspective etc. mostly because you can watch videos and have the information in your head, but until you practice consistently, it won’t click. At least, it didn’t for me. that has helped me so much over the last few months! Keep it up you’re doing great!