Im also no pro but when i try to draw tree, iwas drawing leaves ;) it make its more detail';)

Try looking at various references of other trees on this website.

Your first tree has all the light colors at the top left and most of the dark colors at the bottom right.  This is good if you're shading a ball, but tree folliage has darker "holes" all over the place and only the highlights should be at the top left...maybe even a brighter color.  Also, I'd loose that darker outline around the folliage...on the trunk it looks fine.

EDIT:  Here's a quick edit to show what I was explaining.  I added a yellowish highlight color and darkened the upper part of the trunk a touch.  I've seen trees shaded/textured all sorts of ways.  I think it's very style specific. 

Edited by dpixel - 14 December 2009 at 3:24pm

Did another reshade.

Is the shading for the tree right?



If it's right will start to add details.

The first thing I noticed is there was a lot of colors.  I counted 24.  And a lot of them were so close, it was hard to tell them apart. 
Another thing, which you'll hear a lot around here, is not enough contrast.  Pixel art looks better with higher contrast.  Another words, if you kept the lightest color from the 1st tree and from there create a color ramp to the darkest color of the 3rd tree, this would look better in terms of contrast.

Anyway, my edit took this a step further.  I added even a darker color to the foliage to create more contrast.  I also added a lighter color to the trunk for highlights.  Even with the 2 colors I added, I took the total color count down to 12 (including the white background).  I also removed some of the mirroring not only on the foliage, but the trunk too.

Like I said earlier, I'm not the best at this, but I tried to keep somewhat of the leafy style you had.  I spent about a half hour on this edit....I need the practice too.