First pixel art attempt, help!

[StonedStone]

First of all, excuse my English.

I finally decided to create my first pixel art. I've read lots of tutorials and I think I'm... kinda ready.
A tree was the first thing I wanted to try. I read some tutorials, but I the leaves don't look nice at all. (The bottom part is not finished)



I've redone this almost eight times, and I dont know what to do anymore. I'd like some help, if possible?

[Pix3M]

500x500 is not a good size for a beginner to work with. Start 64x64 or smaller; the smaller the easier.

[dpixel]

Your leaf pattern is not bad but lacks depth...it should blend from light to dark gradually which would add shape as well.  And speaking of shape, it doesn't "read" tree all that well. 
I agree with Pix3M, a smaller canvas would be easier to start with.

Here's a quick redo using the top most part:

[StonedStone]

Do you know an easier leaf pattern? I find this one kind of difficult or tricky

[dpixel]

I don't think there are any 'set' leaf patterns.  Just scupt with pixels what works for you.  Study other pixel trees would be my best advice.

[StarRaven]

I personally really like your leaves. They look more like feathers than leaves, though, especially combined with the gold color.

To make them look more leaf-like, make them pointier. :3

(But I kind of want to see more feather-tree.)

[Decroded]

Just some quick ideas...
1) Smaller size as mentioned.
2) Define some clumps using blocks of shade.
3) Don't put so much big gaps of that mid-tone between the leaves. Bring them closer together.
4) You can break up the clumps by adding a few "layers" of leaves, with shadow underneath. This really depends on the foliage and branch structure you're imagining. Alternatively you can break up larger clumps by having gaps between smaller clumps of leaves.
Here's an example of the second option - http://3.bp.blogspot.com/-ywQENOo-Hbs/UHEgG9dlEcI/AAAAAAAABnA/KeZitCThL3s/s1600/Mango_01.png.