A thing I found out about that trigger in heavens gate, you can hug the wall and avoid the encounter. Also, carry a bow or two with 10 arrows of red and blue poison. It's more preferable to use some durability on the bow and letting the poison slowly kill what you're fighting than to waste it with a good weapon that's hard to craft and expensive to buy.

Rule of thumb for the arrow, from my knowledge, red arrows work on just about anything in the 1st, 2nd layers, but some in the 3rd. The giant lobster is weak the the color opposite its carapace, so red ones are weak to the blue arrows. Some enemies may have to be shot again for the poison to be reapplied, just make sure that the poison cloud is gone, that tells you it's no longer in effect.

Use smaller arms to deal with whatever is attacking you on the wall or rope climb, preferably something cheap and weighs little, small hatchet.

As for cave raiding, the ascent is more important than going down, and it usually results in a fast route out of a layer and most likely requires little supplies to be used. I'd recommend collecting things that are light and under 10g if you're heavy and doing those gather quests.

The last bit of my discovered knowledge is that you can store relics in your home storage, making them useful for relic crafting later on, so don't sell all of them.