From a friendly point of view, your signature is ok.
I won't go into detail but the the first thing that captures my eyes is the use of textography. Not only is the text somewhat blurry, but it blends too well into the background making it hard to read. Simply changing the stroke of the text to appropriate colours should do the trick.The mono colour also makes the signature boring. Unless you were working to a specific design there is never a reason to change the main stock image picture to a colour to match the scheme but instead to change the scheme to match the stock image.
http://kuler.adobe.com/ <<Here's an awesome site for you to try out. Remember as a designer you first need to master the basics which is colour, placement, contrast and all that stuff.
If you want Photoshop CS3, hit me up. You know where to find me

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I also really like Alantie's signature. The only problem is the black border making it look like that the characters have been suddenly cut off.