I started out with a set of goals: 1) B+ system (did not want to spend a ton of money), 2) system that was not too big physically, 3)digital emphasis, 4) good bass so I could enjoy rock and jazz, 5) good vocals. Next, I researched ads and reviews (yeah, I know now not to rely too much on that!) Next, I found three reasonably high end stores near Boston. Then, I listened to a lot of equipment in sound rooms, narrowed things down and brought a bunch of stuff home and listened to it. Finally, I made the buy -- focused on speakers first, then pre-amp/amp combination and finally the CD player.
With upgrades, I bought a lot of cables on Audiogon and asked a lot of questions about system matches to narrow down the options. I upgraded my amps based on ads followed up by a home trial period in conjunction with buying at a great price. Ditto the speakers. Home trial -- testing for dramatically improved performance on all critical fronts and combining it with a sharp pencil around pricing. Generally, for the upgrades, it was home trial, marked improvement in performance and very good deals that drove the decisions. I would not have upgraded components or speakers unless it was a giant leap forward (incrementalism is just so expensive!)
How would I do it now? Ideally, I would read more reviews here, spend more time listening to systems at the shows and in various high end audio shops (e.g., Goodwins in Boston), beg for invitations from fellow Audiogoners to listen to the great systems that they built and I would narrow down the philosophy before buying. The philosophy would be in very different terms than before: I would really think through analog vs. digital (or both), high power vs. low power, type of amp design (e.g., tube), and type of speaker (e.g., bass reflex). The second two decisions would have to follow the first two. I would then set a budget and general budget ratios for the equipment and cables. Certainly, the room dimensions and surfaces are important and I would likely include treatments in the budget. That would be in a perfect world. Since I'm nowhere near perfect ... (By the way, while I would like to think that I would buy much more equipment used, I would not do that if I found the equipment at a dealership and that dealer spent quality time with me)
I did not discover Audiogon until after I made many of my initial purchases. I am still discovering new ways that members have configured systems that just sound awesome!