This is some GM advice from an OSR game I really like called Crowns. While they are intended for that system, there is a lot of good advice for any system. I might drop back by this post in the morning to offer more some of my own advice (particularly I can offer some technical advice regarding DMing on discord) & share some links to people much smart than me about these things. But I need to get some sleep. Good night/morning depending on where you're located.

GM Advice

Social Interaction

Players normally should not need to roll for social interactions unless they are trying to avoid consequences.

Perception Checks

Saves to view a room are not necessary unless the players are trying to avoid consequences. For example, an adventurer making a save to not be ambushed.

Telegraphing Danger

Give the players warnings when danger is near, through sounds, smells, or sight.

A potentially fun moment is the players admitting, “we’re walking into an ambush” before getting ambushed and losing the fight.

A potentially upsetting moment is the players getting ambushed without warning and then losing the fight.

Do not pull punches, but don’t shoot chickens with buckshot. Get a feeling for what your players can and can’t handle.

Don't Stall the Game

Do not make the players perform a save that, if the players fail, will utterly halt progression.

If success is mandatory to progress, don’t leave it up to chance.

Reward Ingenuity

If the players get smart and solve your puzzle or kill the big, bad, evil, boss monster, reward them. There will be other, probably easier, puzzles and battles where they struggle for no conceivable reason, let them enjoy this small victory.

When to Ask for Saves

The GM should only ask for saves when the players are trying to avoid the possible consequences for their actions.

Consequences

The consequences players suffer or that they will be rewarded by should be telegraphed and partially explained before they roll.

Create multiple failure states. Maybe if the players fail a roll, what they want still happens, but so does an additional consequence.

• Damage. 3 levels of damage: minor, moderate, major. Anything above it is considered deadly.
• Conditions. The exhausted or panicked conditions are good-old reliables
• Lose time. Waste a turn in the dungeon, causing torches to burn low and wandering monsters to make visits.
• Mark dots. Mark 1-3 dots on an item (all items can take damage in Crowns & are expendable yet repairable so this one might not apply to your game)
• Make noise. If in a dungeon, roll a wandering monsters check

Alternatives to Death

If the players lose a fight, but you do not want to kill them, try kidnapping them instead.

If the threat is human, maybe they want to get information from the players, sell them as slaves, or ransom them off.

If the threat is a monster, maybe it takes them back to eat them later or to feed them to its babies, or to sacrifice to its dark overlord.

There are some monsters (such as golems or undead) that are mindless and will kill wantonly. Telegraph this to the players so they are not surprised when it happens.