Well, there are some principles when looking for good material, but they are not:
- Age of the tree on the label. Commercial nurseries grow cuttings and give them the age of the mother tree.
- Shape of the tree. Symmetrical "S" shapes are not good for bonsai.
But usually one can find old, thick, unusually shaped material on the back of the garden centers, for almost nothing $$$. This includes good root spread, flare, and sometimes taper.
With a starting material like that, one chops it down to the first branch, repot it in good soil mix, wire the branchlets to give them direction, and pray for backbudding. Not too much TLC, and patience.
To sum it up, if it's cheap,S shaped and in a blue glazed bonsai pot full of organic soil, don't buy it.

Thank you so much Clicio! These pieces of advice will come in handy when I will soon start my hunt for new material! Hopefully this time I will be prepared to judge a good tree

Røng wrote:

I am going to buy some more bonsai trees soon in order to practice my skills

one thing you have to remember is you do not buy bonsai trees. you buy trees then train them to become bonsai trees. unless you are ready to spend a good share of money then yes maybe you can buy a bonsai tree.
on another note before buying a tree please make sure you know the species. this way you can find out how to care for it. no sense in buying a tree and not knowing the species or how to care for it.

Oh yes, definitely, Crent! I am sorry for the misunderstanding, I have gotten myself way too into Bonsai that i start calling every miniature tree one so sorry for that. Luckily we have the species label on BonsaiEmpire so I will look on that while searching for good material. Thanks for the advice!