There are plenty of sites that talks about how to get started, how to stretch your budget, where to begin when building a home bar. This is not what I will do, I assume you have the funds to purchase what you need. If not in one go, and that is most likely the scenario, you decide where to start and the pace. Ideally, you find the drink you like and start there, and then try to expand from those ingredients, adding one or two more, as you experiment. A way to test is off course to go to bar and try out the drink before purchasing a specialty liquor only to the realize, you never want to drink anything with Malibu Rum ever again.
To have a working Cabinet you must have a few things beyond the spirits. Tools, glasses and other accessories.