Well, here goes a rank beginner and his method of making trees:
1. Go out and cut some limbs. I get mine from my yard and from work. I try to be particular, look for small limbs that have a forking structure that resembles a full size tree. If you can't find limbs that have a nice three dimensional forking structure, that is okay. We can add some other smaller limbs to the "tree" to fill it out... so you will also need some extra limbs for this. Certain species lend themselves well, others don't. Scout around your area to discover what works and what doesn't. Also, some of the species are more fragile than others. You'll figure it out. Trial and error.
1. Go out and cut some limbs. I get mine from my yard and from work. I try to be particular, look for small limbs that have a forking structure that resembles a full size tree. If you can't find limbs that have a nice three dimensional forking structure, that is okay. We can add some other smaller limbs to the "tree" to fill it out... so you will also need some extra limbs for this. Certain species lend themselves well, others don't. Scout around your area to discover what works and what doesn't. Also, some of the species are more fragile than others. You'll figure it out. Trial and error.