There are almost as many ways of collecting as there are collectors. Many variations also exist within the military buttons that we collect. This variety affords us opportunity and allows for the numerous sub fields and interest areas within our larger hobby. It also allows plenty of room for everyone to find a comfortable corner of their own. If you are a developing collector looking for such a niche or are considering expanding or shifting your interest, I offer you some general thoughts:

1. Specialize, but don't define your interest too narrowly. Pick a branch of service, a state, (or better, a manageable combination) and focus your attention, efforts, and energies.
2. Find a focus. Try looking at your points of interest. This might be the state you call home, or the uniform buttons from the state or branch of service in which an ancestor served. It could also be a specific period (e.g., Rev War, Mexican War, Spanish-American War, or etc.). Perhaps you attended or have a connection to a military institute or academy. Your considerations could also be purely aesthetic.
3. As you can see, there are lots of directions but, at the risk of oversimplifying, there are two basic strategies: collect the more readily available buttons and work your way up to the scarcer ones; or, buy the rare ones now and come back and fill in the gaps later.