My process was laughably different than this one... I feel like a scrub now, lol. Basically I did this:
1. Learn characters moveset in-depth
2. Learn really short, easy combos (no BNBs)
3. Learn to hitconfirm those combos really well
4. Learn to pressure, zone, block
5. Learn spacing, how to use the entirety of my character's moveset effectively
6. Learn a few more short combos (still no BNBs =[ ) and how to hit confirm them/go into them from common attacks
I still haven't learned BNBs, which is what I'm trying to do now (getting a stick soon, so that may help). For the most part I survive on basics... I did learn a few matchup specifics (mostly just the couple of characters used by my friends), but nothing too in-depth. Now that I have a local to go to I hope to drastically improve my character specific matchups, improve my fundamentals through practice, and learn to apply BNBs once I know them in actual matches.