Ullr’s dictionary of suggested map markers, with minimal spoilers.

I love the font in this game. All the letters look like runes cut with the tip of your knife. It's very good.
Here's a list of how I use the map markers. Please feel free to comment where you think your system is more efficient.

TLDR – I use which biome the icons are in and label them with B, C, D, L, M, P, R, S, T, W and ?

The fire – I only use this at waypoints where I've built a fire to get a quick rested bonus. If it has a name, it has a warp door.
– I have never used bonfires in the swamp but I love the idea and will probably do so on future runs.

The house:
– In the Meadows it's a structure with enough wood to be worth coming back to harvest with a workbench. Labeled with a V it's a village, multiple structures definitely worth coming back to harvest for wood. DV if it's a dangerous village.
– In the forest it's enough stone to be worth harvesting with a workbench and a stonecutter. Marked with a T it's a tower in good enough shape to be worth using as a waypoint.
– In the swamp I might label a house with a T if I find a tower worth making into a defensible waypoint.
– In the mountains, labeled S it's just stone to come back and harvest. T for a tower, C for a castle. P for those pit basement structures. (The only place I use P on the whole map. I found one right next to a rock and built a very cool gigantic underground basement. These structures do also appear in the swamp but generally the trees are the place to go if you want to build there)
– a plains house gets the same T or V as the Meadows.
– in the Mist a house gets a D or occasionally an S, if there's no crypt oops only monsters.
– A house in any biome labeled with a❓ is a possible future base location.

In the forest I label the anvils with C or T if it's a crypt or a cave. In other biomes there is no label.

The dot is for resources. M is for Mushrooms, B is for berries in any biome but the mist where you can find bs and b**s. I only stop to mark them if there are five or more. Thistles and dandelions are so visible I don't bother.
– in the forest, C and T
– in the mountains, S
– in the plains, T
– in the ocean, L
– in the mist, A, B and R

Finally the standing stone 🪨
With a name it's a Warp door.
B for boar Stones, T for those rings where you can find treasure, D for dwarf nests, D and S in the swamp, R for the rest of the standing stones with messages on them because I have the mod Rune_Magic by hyleanlegend.

Thanks for reading. If folks are curious just ask and maybe I'll do another list of the 50 plus mods I'm running in my solo play.