Yeah, mainly practice, even if it doesn't look good practice always helps. Your main points are needing to learn blending/smudging. Besides that C4Ds are good for starters...
Try to Smudge and brush the render in different layers to make a more effective blend , and also use stocks for Bgs
Yeah I can see what you're trying to do. The render is pretty big though. Follow Fluxens advice, smudge the render into the background a bit. Maybe slap a few C4ds in too. But tutorials are definately the way to go to get you on your feet