I agree its very messy and low quality effects. Never add a grunge effect to a spacy image. Also i feel the comets are over done. There are way to many on there.

I have to agree that its very over sharpened

This has some potential in it. The light blue flare on the bottom right is very random and not needed at all.

Its not over saturated, its over sharpened and a bit over contrasted on the dark side of it. Also i agreed its very plain. Theres really nothing to look at. Add some effects and different colors.

In your motto, it says graphic designer... I don't think I would call you a graphic designer for putting ugly text on pictures.
And being a graphic designer is a professional job.
A graphics artist ...

Its not bad i feel like you still have much to learn. Some of them had bad text, low quality effects, random busy effects, and bad color schemes. But there are some that have nice textures which were ...

Nice work. I like it 9/10. I feel like the underline on the words kills it. Try creating a clipping mask on the text with the texture in the middle.

I don't only want to do avatars and sigs, any other things you think I can do?

Depends What your used to. you can try different type of signatures. when i means that, using a render, creating effec ...

Not bad. Some seems really fake. Try using some Selective Color to bring out the colors more and make it seem more real

3/10
All it is, is a render, a cropped picture of the render (the hand) and drop shadow text