The artist will always be the worst critic of their work, so its normal that you'll speak the way you do about your work... but what you have to work on is keeping the thought "practice = improvement" because really thats the truth. Here's an example of something I did a year ago, and something I did recently..
This sig is the very first one I ever did. I only knew the very basics and thats why I don't have the nicest glows.
Here's a sig I did last week for a sig challenge I hold at
my forum...
And here you can see the sig I just finished with Xean, where I was responsible for the image enhancements
As helpful advice to you, I recommend going to sites like
www.good-tutorials.com as they will have great tutorials to teach you new effects and things (everytime I go there I always learn something new about PS). In regards to your sigs, I think the creativity is great, you do have good ideas for poses and placement and even font. The only thing that is a bit of a problem for me is your choice of colors for your outlines and glows, I don't feel they match up with everything else in the sig... but then again art is all about the opinion of the person so not everyone will agree on what they deem "beautiful". So with that said, just keep practicing and try to learn other effects, play around and you'll see over time that you will have improvement.