1. Start small. Have a budget and stick to it. I would start at most at 2% of my annual income and go no further for my first college try.
2. Understand the nomenclature behind the hobby. Figure out basic electronic terms like impedance, watts, audio frequency, bit rate/depth, bloom, etc. That describes what your equipment can do. Then learn about words like ‘detail’, ‘darkness’, ‘dynamics’, ‘harsh’, etc.
3. Go through the collection of music that you have. Figure out what you listen to most. Figure out how you like to listen to it. If you like to listen to hip hop on digital media, but you prefer listening to that with your headphones on (e.g. if you are from the East Coast), don’t shell out a lot on speakers. If you like to listen to vinyl recordings of old punk records, then fidelity isn’t nearly as important as the robustness of the equipment. If you like listening to classical music composed before 1920, then you want to optimize for clarity, a wide sound stage if you like opera (or Wagner), etc etc.
4. Buy used if you can help it.
5. Make your own cables. Saves a buttload of money.