Step 1:
I made leaf papers in various sizes and two different greens.
Prefold in half.

Step 6:
Make an outside reverse fold over these lines.

Step 5:
Make zig-zag folds over these lines.
Unfold afterwards.

Step 2:
Fold over these two lines.

Step 4:
Fold in half over the prefolded line.

Step 3:
Fold over these two lines.

Step 10:
Wrap 2 large papers (white and brown or light brown and dark brown) around a metal- / florist wire.

Step 8:
Done......

Step 9:
I made about 80 leaves for my Birch Tree.

Step 7:
Bend / curve / crumple a little, to make the leaf look more natural.

Step 16:
Make five twigs out of smaller papers, they're also made the same way as the main stem.

Step 15:
The branch is glued to the lower part of the main stem.

Step 12:
Bend the top and bottom in different directions, see next picture as example.

Step 11:
Twist tight around the metal- / florist wire.

Step 14:
The papers for the branch are 1/3 the length of the papers for the main stem. It's made the same way as the large main stem.

Step 13:
This is the main stem of the tree.

Step 21:
And this is the upper bunch.

Step 19:
So, this is the base of the bonsai tree.
Finally I glued all leafs to the twigs.

Step 20:
I made two bunches with leaves, this is the lower bunch.

Step 18:
This is where I glued the twigs to the model.

Step 17:
All 80 leaves are glued to the twigs.