T3H gallery

http://www.shrani.si/f/2e/DD/2xdKrDU4/mario-best.gif
http://www.shrani.si/f/3M/PZ/1Jq7dzzf/evil-is.gif
http://www.shrani.si/f/3R/i/2CZnhYFg/84nt83ncfn.gif
http://www.shrani.si/f/2E/YN/vtTMxxp/abstract.gif
http://www.shrani.si/f/1k/EL/3687S3tM/mario-lines.gif
here are some of my sigs please tell me what should i improve

The second is the best by far. Really good, wouldn't mind a tutorial if possible bud.

http://www.shrani.si/f/2e/DD/2xdKrDU4/mario-best.gif

This is my favourite one.
The effects are fitting as they look smooth and unrealistic, which they should be because the art style of Mario is like that.
It has a decent background too; looks like you've got some good smudging there.
Just the one thing that ruins it - the colours. They are far too monotone.
Everything else is quite decent though. Work on colouring. :D