How do I progress through mine levels?

[CryCryBaby]

do bone clay and iron spiraling

And I will add. Spiraling of everything. Not only clay and iron.
The best bones are not only for white clay, but also for compost baskets.
The best meat / crop for compost.
The best flax for a herbalist table.
The best skins for leather straps to make the best rope, for the best potter's wheel.
The best clothes and gilding, if you do not want to spend LP on farming.
Either you spiral everything at once, or something will be missing in the end.

[AlexNT]

Spiraling of everything. Not only clay and iron.

This is off-topic, but I've noticed this term being used differently in Russian-speaking community. Or it could be that the meaning has changed while I wasn't playing. Would be interesting to hear opinions from non-Russian speakers.

When it was first coined, the term "Spiraling" applied specifically to iron quality, because there are multiple products involved in a multi-stage, cyclical process.

E.g. you don't "spiral" flax (because no other products are involved in doing so), you just grow increasingly high quality of it. Same with livestock.

[friendlinzh]

Dig another hole into lvl5 in hopes for a softer spot

[AlexNT]

Dig another hole into lvl5 in hopes for a softer spot

It ended up being "eat into another 50 points of STR and be able to dig almost everything".

[azrid]

you welcome

[MagicManICT]

Dig another hole into lvl5 in hopes for a softer spot

It ended up being "eat into another 50 points of STR and be able to dig almost everything".

Sometimes this is all you need. Sometimes, it takes 100 points.

Your earlier question about spiraling: I've usually rebuilt my first kilns, smelters, and finery forge by the end of week one, again end of week two to three, and again about a month later depending on how quickly I find better clay spots. A lot depends on how much of a quality jump I'm getting. Going from 20-40, then 40-60 is big. 60-70 not so much. After 60, it's more being able to source materials for bone clay, and the speed at which you can get your better quality, sometimes you have to settle for 5 points at a time or less as any increase in quality is going to be better than the current workstations. If I recall the first post I had seen on quality spiraling, the village doing it was settling for one or two points at a time, but it was easier to source the cave clay at the time.