https://pixeljoint.com/pixelart/123693.htm

I think row 3,column 3 would be most useful for your shapes.

thanks <3 can you name me some refrence that might help or just practice will improve it ?

The pixel work is good. The shading needs improvement. The trunk suggests top left light direction, and leafs should have the same. The shading pattern also should be redone to show volume. It is very flat now.