Select the species of tree. When selecting a tree species its important to consider your geographic location. Some trees lose their leaves in the winter and require the temperature to drop below freezing so that they can enter a dormant state and prepare for the spring. Other trees will not survive long in the freezing weather. Some trees will require a lot of water during a hot summer while others are heat hardy. Research the kind of trees that do well in your area. The three varieties of tree most commonly used for bonsai are: 1) Ficus; 2) Juniper; and 3) Chinese Elm.
Select the size of your bonsai. Bonsai trees can be as anywhere from miniature (6 inches tall) to large bonsai (up to 3 ft tall). Decide what size bonsai you would like before actually going out to select the plant.
Select the plant. Once you have decided which kind and what size bonsai you would like, you can go to a nursery or a bonsai shop and select the plant that you will use to make your bonsai tree. When choosing a plant, look for leaf color to make sure that the plant is healthy. Then look around at the selection of plants and imagine what each plant would look like after it is pruned. It's important to visualize the bonsai before you buy the plant and bring it home. You do not want to bring a plant home only to decide that it isn't immediately suitable to be a bonsai.
Select a pot. Selecting the right pot has a lot to do with the desired size and style of the plant. Select a shape and color that you personally find aesthetically pleasing. The pot must be large enough to allow enough soil to cover the roots of the plant. You do not want to have such a small amount of soil in the pot that the tree roots can not retain moisture. You will kill the plant if you do not have a large enough pot. At the same time, you want to maintain the illusion of nature and select a pot just large enough to support the tree. The idea of a bonsai is to balance the pot with the plant and make the plant look like a miniature tree. Some bonsai pots do not come with pre-drilled drainage holes. If you do not have a drill that will cut through ceramic, then make sure you purchase a pot with pre-drilled drainage holes.
Prepare the tree. Prune the tree to the desired shape. Wire any branches that need to be wired. Remove the plant from its existing pot and water the roots. Most of the roots will be cut before the plant is repotted into the bonsai pot. Cut away enough roots so that the root system can fit securely in the new pot with the proper amount of soil.
Pot the tree. Install mesh screens over the drainage holes to prevent soil erosion. Add some well draining soil to the pot and then place the tree into the pot. Do not use regular potting soil for your bonsai, it holds too much water and may drown the tree. Before covering the top of the roots with soil, position the tree in the desired orientation. Run a heavy gauge wire from the bottom of the pot through the drainage holes on the bottom of the pot. Tie the wire around the root system in order to hold the plant in place. Finish adding well draining soil to the pot. If it is warm out, make sure to keep the newly planted tree watered well until the roots get established in the new pot. Trees from temperate climates should only be potted in the spring. Trees from tropical climates can be potted whenever the weather is warm.
Experiment. You can experiment with many kinds of trees, plants and shrubs. Try making bonsai with plants native to your area.
Join a club. If you can't find a local one, there is one online called the Internet Bonsai Club.