show don't tell...
...is shit.
Personally, I'd rephrase that as know what to tell.
When it comes to descriptions or detailing actions, it's most important to decide how much the POV character knows, and what you want to convey.
For example, if I have a character that's furious, I will tell the audience that they are furious, that red is clouding their vision, and that they are trembling, hands in fists: i.e., everything that they are explicitly aware of. Because I think they'd know if they're angry, like a normal person...
But I won't tell the audience that they are jealous, because they don't currently know that they're in love with their best friend. They only know that it's upsetting them, and that seeing the best friend kiss someone else feels wrong. So that's all I'll tell the audience, and leave the rest up to context and nuance, because audiences are not stupid. They can figure that bit out.
As a general rule (but remember that there are always exceptions), it is best to only describe or tell what the POV character is aware of, to the level that they have self-awareness. You could think of it like how a child or emotionally stunted individual might not have a perfect grasp of their self-awareness and hence not realise what emotions they are experiencing — and that's when you don't explicitly state their emotional state — while an assassin or trained politician who's constantly monitoring their own and others' emotions might immediately identify that they're feeling upset, sad, happy, or furious.
All information should be filtered through their perspective, and hence the description and prose should reflect this.
Please, for the love of everything fruity and whimsical, do not shy away from writing 'I'm furious' or 'I want to cry' because an english teacher told you 'show don't tell'.
I think of a character's perspective of their story as the ocean — while you don't tell the audience the deep-sea currents, or the true, underlying cause of their actions and emotions unless the character is also aware, you can instead describe the water's surface. Describing or telling the audience things that the characters are explicitly aware of, as though they are someone swimming in the shallows — the waves, the warmth of the sun, things that are immediately relevant and known — is more immersive.
If you ONLY ever describe actions, and never state a character's thoughts, they are more likely to come off as emotionless. They should be making emotional judgements on their surroundings, other characters, and events, because all of these things will reflect their characterisation and context. The medium of writing is unique from other mediums in that it allows introspection into characters' thoughts; if you do not utilise this, you are essentially writing a screenplay.
Hope this was useful, and have a great day :D
