Borders: You should add a nice border around your SIG and perhaps round the corners off?
Opacity: Behind the "VILLA" text, you could perhaps put the United or Valencia crest (aka logo), with say an opacity of 20%?
Once your SIG is done, you can compress all the layers into one by doing 'Ctrl + E' and then if you want to change the overall colors of your signature then press and hold 'CTRL +U' to bring the hue/saturation dialogue up and simply play around with the settings from there.