I have killed hundreds of trees. In fact, I killed over 100 just for the 6 Year JBP contest. I started with over 1000 seedlings, made 90 cuttings (tossing the rest of the seedlings), culled down to the best 44, and in a year will probably keep 20 and plant the other 24 in landscape
Most of the trees I have killed have been pre-bonsai, or trees that I am experimenting with. Once a tree is established in good soil in a bonsai pot, it is unusual for me to kill it. I can't recall the last tree in a bonsai pot I've killed, particularly if they are special trees. For example, over the years I have gotten six trees from
@Si Nguyen , and I still have all six. I am afraid to kill any of them!
When I started in bonsai, it was pre-Internet, so if you didn't live near a club, you were pretty much dependent upon books and magazines. Now with the Internet, there are many more options to help you learn, but nothing beats hands-on experience.