Okay, I am going to give broader critique's on these - an I may come across as harsh, but please don't take offense; it's my nature:
1) These signatures seem rather small. If they are 100px high, I would say they should be at least 400px wide (my rule of thumb is that the dimensions should usually add up to 500px in a typical tag)
2) Effects - frankly, there are none. All I see is a render, duplicated twice, set at differing opacities, slapped on a background.
3) Things you should begin to learn: blending, flow, depth, composition, effects, and COLORING (very important) are the basics, you can ask me about them if your confused.
4) I'm glad you didn't use text - it's a cardinal mistake made by amateurs and always looks shitty. Nice job not using it.
Hope I didn't seem to rude - I certainly wasn't trying to be. If you need any help or refrences to tutorials, just PM me or post here. I'm happy to help
P.S. What program are you using?