Darkest Dungeon

Hamlet Advice

Prioritize upgrading the wagon, the forge, and the guild. You want a large roster, you want a good selection of hires to choose from, and you want to upgrade and tweak your characters.
Prioritize weapon upgrades over armor upgrades. Better weapons increase your speed and accuracy. Speed is the most important stat in the game.
The abbey and the bar perform roughly the same service. The bar has more random bad events. Neither is particularly important, however, because...
Characters heal stress naturally when left in the hamlet. If you have a large roster, you'll rarely need to spend money on stress healing services at all.
Use the sanitarium early and often. Removing bad quirks and locking in good quirks gets more expensive the higher a character's resolve rises. Disease care is less important, both the plague doctor and the grave robber can have access to disease cures mid-dungeon.

In general, target backrow enemies first. They're usually much more dangerous to your run.
Focus on preventing enemy actions using stuns or finishing them off over healing, unless you've somebody on death's door.
Your characters and your enemies take damage from blights and bleeds at the beginning of their turn, before they act. This can mean an enemy is a dead man walking, barring a clutch enemy heal. There are very few enemy healers in this game.
It's better to fail a mission with your resolve level 3 characters and take a stress hit than to lose the resources you've put into them. Use your judgement. Overconfidence will kill you very quickly, actually.
Camping has two uses; recovery and buffing. Its often better to buff up than to wait until your characters are run down. Skills that prevent nighttime ambush are very good. You can lose all of your recovery and part of your buffs' longevity in the course of the average ambush fight.
Gold is generally better then gems.

Unupgraded characters are expendable. If they have poor quirks (-speed is the worst, compulsive curio use runs a close second, everything else depends on class) or have an affliction, feel free to shoo them off. Or send them on a suicide treasure run if you have nothing better to do.

This isn't explained very well in-game: If you bring an antiquarian on a dungeon run, make sure they investigate all treasure curios, even unlit torches. Their gimmick only works for them, not the whole party.

Outside of Stygian/Bloodmoon difficulty, do not restart your save if bad things happen. The only thing you can lose in Radiant and Darkest difficulty is your time investment, and restarting is just subjecting yourself to a much steeper cost.

There is a convenient informational tool for dungeon prep and curio info at this page: [1]