You should take into consideration the rule of thirds; dont always put the main focal perfectly in the center, it looks weird. Your most recent look very empty, you should add more effects or somthing. You need to work on the text A LOT, you shouldnt just hide it and stick it in the corners. Bring it closer to the focal. How'd i know this, i used to create LOOOADS of sigs like a year ago and got a lot of advice on other forums. Keep improving!