1.) Educate yourself (music appreciation/audio basics) and your ears to what you're hearing
2.) Know yourself (musical and audio sonic/gear preferences - are you basshead, an amp guy, or speakers, vinyl, etc.)
3.) Decide what space you'll be listening in (no point trying to put huge speakers in tiny rooms or shared rooms that must be moved daily)
4.) Set an all inclusive budget (including renovations, travel to hunt for the perfect gear, wifey buy-offs)
5.) With the given space in mind shop first for speakers, then amp, then source(s)
6.) If necessary treat the room.
If it's been awhile, know that most music is streamed (up to CD quality) or downloaded to hard/solid state drives (up to much higher quality). Tapes are limited to a very small crowd. Vinyl is resurging but still in the minority with albums not easy to find or inexpensive. Shopping for audio gear is rarely done in brick and mortar stores any more, now it's done online, at club meetings, and at shows. As a whole audio taste has moved to from looser bass, warmer sound to a very tight/more clinical presentation in the past 30 - 40 years. Tube amps have had a rebound while solid state is moving to new technologies. Prices for a given level of performance has never been better.