Theo, you have some potential and obvious enthusiasm, but there's a few things.
One, as my buddy Docco over there said, make your cuts neater. If you really wanna make good sigs, take time in them and cut out the pics. Either you can do that or go to a website where you can download cut pics. Either way, they need to be neat and precise.
Two, again with Doc, never stretch pics. Ever. Unless there's some point to the picture of it, don't do it. Also, referencing the Future of WWE and some of the beginning ones, try keeping the wrestlers proportionate to each other if you're having the picture next to each others.
Three, text. Text is majorly important in signatures, unless none is present. First, NEVER cut off the main text. Always have it within the sig, like the John Tenta or Foley sigs, unlike the Zack Ryder and second Jack Swagger sigs.
Finally, some extra notes. Always have a border. Not much to say about it. It can be a fancy, 5-10 pixel border, or a 1 pixel dark or light color border. Doesn't matter, just have one. That goes to Doc, too. Also, attempt your own background in sigs by downloading brushes and patterns. You can also make your sigs nicely textured by downloading those patterns and making them nice overlays and such.
That's really all I have to say on the matter, Theo. I hope you become a great sigger, man. Good luck.