Pruning a tree or shrub purchased from a nursery is a great way for beginners to create a bonsai. Select a specimen that has a strong tapering trunk with a good line and many branches. This technique has many advantages for beginners to buying a ready bonsai; it offers a chance for beginners to practice visualizing potential in plants, it is significantly cheaper, if you are not happy with the result, you can always try again, and you obtain instantaneous results (usually within 30 minutes).
Trim off any unnecessary twiggy growth that obscures trunk visibility and one of each pair of opposite branches. For most bonsai styles, branches should be pruned in a way so that branches become shorter ad thinner as you look higher up the trunk. Cut off any twigs that grow from the underside of major branches; this will add a more natural tree like appearance to your bonsai. When trimming the length of branches, remember to trim a little shorter than your desired final length as new growth will appear at cut site.
Remove any awkwardly large leaves and any leaves growing on trunk by pinching leaf stem and twisting off the leaf or cutting the stem with shears. Remember to leave a portion of the original stem still attached to branch. This left over stem will eventually die back and fall off, but forgetting to do so may scar branch tissue or cause die back on branch. Continue pinching or trimming off leaves until you are satisfied with the result.
Every 2-3 years, your bonsai will need to be repotted and have its roots pruned. To do this, remove your tree from its current container and using a root hook or a chopstick, try to remove as much soil as possible while detangling the root mass. Do not worry too much about breaking some roots; you will need to trim many of them off anyways, but remember to never cut off more than 1/3rd of the root mass at one time. Doing so might result in the tree stressing out and dying.