If you don't have much experience with bonsai. I suggest you join a bonsai club. You will learn how to take care of the bonsai and get expert advice and help to work the plants. Most clubs also have members that have suitable trees to sell as well as the tools, wires, media, turn table, and sometimes pots.
Junipers are flexible so they are easy to wire, but they need to be outside plants. They are not house plants. There are other kinds of plants that would make suitable bonsai specimens. But you need to choose one that fits your conditions.
Here is a listing of bonsai clubs around Phoenix.
There are bonsai clubs all over the world, it is a good idea to check out one near you. Bonsai is an art form and takes time and patience. At a club you will get expert advice and help choosing your plant and help with care and training. Beginner bonsai are usually yound starter trees. Advanced bonsai growers usually start with much older trees that have developed "character". Much of the beauty of bonsai is to try to make the tree appear to be old and stressed. That is the point of the windswept, and lightening strike trees. It is also the point of looking for trees that have interesting trunks that looks like they have a few miles on them. The trimming of the canopy is done really to show off the trunk and branch structure as well as to kind of show their gnarliness. You don't want to really see sawed off branches, nature does not make nice saw cuts. People will usually carefully file branches so they look like they were naturally broken off rather than cut or sawed off. Lateral branches are also placed to follow lateral lines and generally a pyrimidal shape.
The difference between topiary and bonsai: Braided trunks, animal sculpture, geometric shapes which show more leaf and not a lot of branching is more topiary.
Bonsai, is the art of mimicking nature in miniature with emphasis on showing more of the trunk, branching and the appearance of age or 'stress'.
A tree in a pot is still a tree in a pot, it does not become bonsai or topiary until it is shaped and carefully trimmed.