What's the ideal once you get to 50? Farm Philosophy tombstones and get some dark light gear then do hard primates or what? I'm still confused on even how to get the relic weapons.
Unfortunately, philosophy tomes were removed from the game in patch 2.2. Now the only way to get Darklight gear is to farm it from the newest 4-man dungeons.
Probably your best bet as a new level 50 is to just run a bunch of dungeons. Dungeons such as Amdapor Keep and Wanderer's Palace are doable with just AF armor and a level 55 weapon, particularly if you get teammates who are better geared. Those dungeons drop level 55 armor, which is a slight step up. The first set of Hard Mode Dungeons (Haukke and Copperbell, as well as Pharos Sirius) drop level 60 armor, while the second set of Hard Mode dungeons (Halatali and Brayflox) drop level 70 armor. If you have the gil, you can also buy level 70 crafted armor (Darksteel, Vanya Silk, Gryphonskin). Talking to a crafter and buying the materials they need using GC seals might make that cheaper.
However, the big thing is probably the Labyrinth of the Ancients. You can get ilvl 80 gear there, and it can practically be done with AF armor. It is a lot easier to collect that gear now too, since they removed the one drop per week limit.
While running all of these dungeons, you can get myth tomes, which you can trade in for ilvl 90 AF +1 gear. At this point in FF XIV, after patch 2.2, it is unlikely you will be able to collect a full set of gear in a reasonable time frame prior to myth gear, so you will probably be using a patchwork of different gear sets for a while. Just focus on collecting what upgrades you can.
Anyways, you can start your Relic Quest as soon as you beat the game. It will guide you through the post-game to a certain degree. It has a lot of steps, though. I believe it starts in Revenant's Toll. Just follow the quest one step at a time. Eventually, it will involve fighting the hard-mode Primals in order. There is not too much point to beating them until you get that far in the quest, unless you want to try and get a Primal weapon.
You don't need ilvl70 gear to beat all of the Primals though. I was able to beat HM Ifrit the same day I first cleared Praetorium. Garuda is somewhat harder, but not too bad. Traditionally, you needed at least full Darklight (average ilvl 70 gear) to stand a chance at surviving HM Titan, but the 2.2 echo buff loosens that up a bit, but you will need good gear for doing anything past HM Titan.
Probably the best place to get a good weapon prior to your Relic is from continuing the story and fighting God King Moggle Mog XII. You can get ilvl 75 weapons from that fight.