im guessing you are using the gimp. tough program, try photoshop if you can get it.
tips for improvement:
stretching your backgrounds does not look good. Try simple stock photos for texture, and incorporate new techniques as you get better.
Texting is hard, keep it simple and just write the players name, and not a whole lot more.
make sure you use good renders, go to sdsportsfanatic.com, psdcentral.net, or surrealdesignz.com for already cut renders.
and just keep practicing