Ill give some advice and appraisal
1. Fred; I think it needs bit more in it, its a bit empty. The colouring in the background isnt quite right, maybe a little more red needed, i dunno, but it just isnt right. Also i dont like them stars
2. Warnie; Good, again a little too empty but i like the effect on the render, just a few spots were too much effect has been put onto him. (Is it burn the effect?) Other than that, suprisingly the background does go with it slightly, maybe put another Warne render very lightly to give the background a bit more interest.
3. Diver Ron; Like it, best out of the three, the background is interesting with the tech brushes im guessing, maybe something differnt i dunno, but the background is good. Nicely placed Portugal badge, the text is something you need to work on, i think the current font would be suitable for Cristiano but you'd need to find another font for Ronaldo, something which goes with it.
Overall your getting better, your getting away from the old technique of Matt's tut of making backgrounds and your pondering into others, maybe try a stocked image for a background, that sometimes helps
But yeah, your getting better....Hope this help...