The first thing I notice when I'm looking at this piece you've made is that it's quite monotone. The three main colours used in graphics, Red Green and Blue (RGB) are powerful and don't need to be brought out that much. I can see lots of unnecessary light as well, mostly from the bottom-right corner, which you don't really need. So af far as all that goes, I've seen you do better, and you'd need to work on colouring and lighting, which I can help you with if you'd like.
Text is nice, although there really isn't a focal point you've used to put the text, which kinda sucks. Your first one is superior in that retrospect because you don't need text to make a signature image. I would've moved it closer to the focal point, or even bigger and on the robot itself. Also you don't need to go about using the fancy fonts either, I normally go with simple, which is a great start, so maybe start on that.
I can't really think of anything else, escept maybe lose the border. Borders aren't very good on tags, unless you're going for that cliche look where you'd have black strips on the top and bottom, but apart from that which you shouldn't even be doing unless you know how to use it, don't go with borders at all.
On a whole, it's nice. Work on your colours and lighting mostly.
