Your work is actually good.
I am not a great Gfx tbh but A few things I noticed
1.) Lightning needs improvement
2.) Focal points should be more prominent
3.) Blend the render with the back ground, let both the BG and render flow together. Your AB De Villiers sig is great but would have been fabulous with better blending.
4.) Never overdo text. If your not able to blend your text with the BG, then Keep your text as simple as possible and try not having it as one of your main focal points (or don't have text at all).