A Kodansha's manga editor said he met some overseas mangaka-wannabe and read their works, but none of them were better than countless Japanese mangaka candidates. Some of them can draw estimable artistic drawing, but they all are lacking the basic sense and technique of manga, like the use of panel layout and focus line. Most notable is the horrible layout of speech balloons. He always give then advice to consider balloons as parts of your artwork. A tasteless oval balloon is beside the question.

For your interest, one of those techniques is that, when a hero and a bad guy fight, the hero should be in left side of the panel and the bad guy should be in right side of the panel. This theory is true in anime too. Check AKIRA manga and anime if you can.