1. Complete your Legion class order hall campaing in order to unlock artifact weapons and second legendary.
2. Do story line in BFA. You get 2 azerite pieces from each zone + 1 from war campaing. First 4 you unlock will be 280 (+5) and last 3 are gonna be 295(+5) so chooce your traits carefull since you can't those later.
3. Run Mythic Antorus for 240+ gear, 2 piece bonus and relics. You can't really have 4 piece since 300ilv azerite gear will be superior than any bonuses except for very specific builds. In my opinion you should aim for cloak + hands and leave Legs slot for item with your best stats.
Relics are tricky since they count as completly different slot so they can't be traded unless that person had a better one before.
For example if 120lv warrior will get 250 relic but in legion his highest was 245 he won't be able to trade it even despite the fact he might have 390ilv weapon now.
4. Find your trinkets - You can buy reliquished trinkets from Vendor on Vindacar, get few of them in Mythic Antorus, in BFA dungeons and in Legion Mythic dungeons but those are gonna have really low ilvl since we can't do mythic+ anymore
5. You migh wanna reach Revered with armies of legionfall for endless flask (
Repurposed Fel Focuser), Exalted with army of the light for
Lightforged Augment Rune and for food, well - bear tartare is the best one for pretty much everything.
6. Pump your Azerite necklace levels by running Island expeditions, opening drop chests doing dungeons etc.
And that's pretty much all there is