Once you've played for a bit, you get a good idea of where to put portcrystals around the world.
Typically I put the first one I find at the chest scar on the hill a bit to the north of Gran Soren and I keep one at the rest camp on the other side of the quarry (near the Shadow Fort w/ the goblins). These two extra places to warp to in addition to Gran Soren and Cassardis give you pretty good coverage. From there I put a portcrystal at the Bluemoon Tower entrance, and one on the other side of Soulflayer Canyon. By that point you can basically warp all over the world.
I have one outside shadow fort so far.
Keep doing your Wyrm Hunt quests from the dude outside the castle and they lead you to most of the places that I mentioned. Each place he sends you for those 4 quests are pretty good places to put a portcrystal tbh.
I should have put one at the old arisen dudes place. I'm doing the catacombs one now, already did fort and the old arisen one. Gonna do the survey one after. ---
