Here is a tutorial on making wire trees.
You start off with stranded electrical wire.
Strip it bare.
Take a few strands and twist at the bottom only.
As you progress upwards seperate and twist again to form branches from main trunk.
Solder trunk and all branches to create strength and stability.
Now paint the tree brown and the fine ends green.
To add flock glue the tips with PVA glue and flock with dry tea leaves.
This creates a nice autumn\fall tree as below. If you want to change it to a summer keep watching this space.
When creating these remember to do a few at a time and not just one.