I need to to improve my design. (||Getting rejected every time)

Hello, Please give me some suggestion about improving designing concept and skill. I want to do work with flyer and business card. I have been uploading my design but every time getting rejected. What can i do now??? I get approved once after a long time but not regular. My portfolio link here : https://graphicriver.net/user/farhad_hossain/portfolio
Some of my design which rejected.

take a look at the most popular items and see what you are missing.