very good to be noobish. i noticed that you use lots of fragments. still looks good though. keep up the good work.
Pretty OK as first sigs i guess None of them have flow though -- Flow is very important and can be seen in all good sigs. I suggest reading some tuts there is a tut somewhere here on the forum that used the same render as your sig with "frogan" Maybe that would be a good palce to start- it is very detailed and simple --- i can't find it right now but i will edit post when i do
^^Yep keep reading up on some tutorials to learn how to do different effects and how to make them flow well
The sixth signature seems to be like the best. It is good as a "first try". Read some tutorials on flow / depth / lighting. It may helps you.
Hmmm. Work on color. All of these are very very monotone. Also, try to create depth and flow in a tag. That's very important. ^_^ However, I can't expect you to know this. You're a lil' noob. Haha. Read some tutorials.