This is a micro-tutorial about drawing interweaving tree branches. I do not claim this is the best way :-) but it works well for me.
Select Brush tool, set various settings as you like, however, decrease default Spacing (25%) to 8-10%.
Draw your ornaments or branches.
Switch to Eraser tool, set brush size to 15-25% of size you used to draw. Carefully erase...
.. then again and again...
...until there are no intercepting lines.
Author: Vlad Gerasimov