Guys, this forum as about telling people HOW to improve, not telling them they need to... we could ALL use improvement. Either be productive with your feedback or be mute, the choice is simple.
CBCOOLEST: The majority of people on this forum are Photoshop users - many of them pretty advanced. So, though what you are doing is admirable, you may get more work elsewhere as this community likes making their own sigs / banners / avatars. That is not to say you can't learn on this forum. I, as well as many other members, have learned a lot about Design Theory, little Photoshop tricks, and expert techniques that can be applied far beyond what goes on in this forum.
Looking at your work I can tell you are new to art in general. Be more adventurous - experiment with lights and darks, contrasting colors, try using filters and overlaying multiple layer blend modes. Though I rarely use effects other than Blur, I know what each and every single one of them does so that I will know where to turn if I, or someone I am helping, needs a particular effect created. It is good to start with a finished product in mind - if you know what you want it to look like before you start then you will better be able to judge your finished product because you can compare it with the image in your mind.
Finally, try and stick with a set style throughout the image. If you are going to be using photos then make sure you use only photos. Like in your "Front Cover #2" image you have photorealistic images of speakers and a disco ball (images that have a lot of shading and detail) but the majority of your background is a solid color (not a lot of contrast or detail). The result is the detailed images look out of place.
Just some things to think about. I urge you to stay a part of this community and learn from those that have more experience, but at the same time you should try and join non photoshop related forums and make banners for people there because you are right, practice makes perfect. In my opinion a very active community that has a lot of people in need of good artists is the game maker community
http://gmc.yoyogames.com/
(there is a sub-forum at the bottom for all things graphics related)
That forum has a TON of members and is constantly growing. People make games using this program called Game Maker so there is a constant supply of needy programmers looking for artists. You should fit right in!
Good Luck
