I'm digging the outside bars of the Elisha Cuthbert one, first time I see that. The sig needs work tho, the effects in her body don't look good, bg colors are boring and text is bad. For the others, I think you are using c4ds too much. They are standing out more than your focals, except for the Lil' Wayne sig, it's the best of them imo.
im digging the green one, im not to sure if I like the keeler one looks like you tossed it together in a few minutes..you can do better :lol:
the first and last ones are the best. they go together the best and have good focal points. the lighting in the 2nd to last one is weird. it's like the guy is outside of the c4ds and he's not really part of the tag. they seems to be sectioned off too much, and the transitions are a bit rough. work on the blending and transitions with light sources and colors within each sig and I think you'll get the results you're looking for. don't worry, you're off to a really good start!!
I like the first one the most but the text doesn't seem to fit very well in any of the tags IMO except for the abstract.