Definitely your best, great color scheme, the bubble things are great. Smudging is awesome, you can really tell how much work you put into it. It's truly amazing for a beginner.
Ok, now for the critique, no text, try to download some fonts from dafont.com that you think would go with the tag, or maybe just add no text at all.
It could use some lighting, and the render needs to be sharpened, maybe crop some off the tag it seems kinda too big. Other than that, you could use that sig and be proud of it!
I kinda see it as I do my sig, it just stumbled along one step after another until it was finally perfected and became your best.