Various Artists Album Cover

(For any album you have that was made by various artist that you don't have a cover to.) I'm having trouble figuring out how to make these space style album covers, and album covers in general. I don't know if it's just because I made them, but whenever I look at my album covers It just feels like they don't look like a REAL album cover. To me it just feels like they don't have that OFFICIAL look to them. I'm trying to figure out what I can do to improve this. So if you know of any tutorials on how to make a good space album cover please let me know.