Where is the tutorial you followed, im gonna murder the uploader.
This is gonna sound harsh, but thats how i give CnC.
Text - In the corner, shows me your a beginner, look up the rule of thirds, and use that for both text and render placement.
Render - Use rule of thirds, also always hold in shift when resizing, he looks a bit squashed.
Colors - You got green C4Ds, with a blue stock, with yellow text. You wanna have it all flow, nevertheless your situation can be resolved with gradient maps and filters, but that wouldnt help this piece.
Believe me Ive seen worst first pieces, keep reading the tuts and learn the basics of art (not just the photoshop tools, but those are important too) and you'll be making great pieces.