As i work in graphical design for Dragonbyte-tech i will try to help you improve on this a little more with some helpful feedback (or at least i hope it will be helpful)
I'm going to assume your using photoshop or GIMP to make your signatures so please tell me if you don't understand anything i've said (i'm going to talk photoshop terminology here)
ok first thing is first, the background works well with the gun image but the gun image is kind of drowned out by all the text in the corners, a good signature uses very little text and the text shouldn't be all that noticeable, for instance if you want to add the glow to your text try using a size 2 or 3 glow and reducing the opacity to around 80 or so, for signature like yours i'd recomend either a white glow or a glow that uses a color from your background (maybe one of those lighter greens on the left side).
Text positioning is a big thing in graphical work, and can mean the difference between something stupid and something awesome, take no offense at this but the positioning of your text could be miles better, i'd of suggested maybe making the "don't smile" text around 13-14px big and the guys name around 16-18 (if you want the text to be big) and position the "Dont smile" above the name or have a play about with different positions.
Also i think your main image focus is a liitle too plain, if you look at your signature theres a lot of blank space which is taken up by background so when a person looks at it they are drawn more to the background rather than the central image (which is bad as backgrounds are a menas of blending the sig with the objects in it and shouldn't be the center of eye contact) when i first looked at your signature i didn't notice the gun in the middle untill about 6 seconds into looking at it i was too drawn to the text and big open space.
for a signature like this you may want to consider using a smaller signature size, heres a little guide on how i personally make signatures:
large signature: 150px x 550px
medium signature: 128px x 500px
small signature: 130px x 420px
of course you don't have to use these but i think these are great sizes for whatever signatures your making.
For this signature i'd of gone more with the smaller size so that your background isn't taking up all the space. maybe try adding some other focal points to your signature to enhance it further.
not a bad attempt but i think with some practice you can do much better