you are writing a novel, not a screenplay
this means that you can exposit in the narration, rather than in dialogue. that's what the narration is for. there is absolutely no reason that all of your exposition needs to be in dialogue. in my opinion it shouldn't be, because this is one of the things about audiovisual formats like film that can be really awkward and conspicuous if not done well. this is a major strength of prose; feel free to use it.
sometimes, if it's very obvious who's speaking, you don't need a dialogue tag. otherwise, just use "said." use "said" (or something fairly neutral like "responded" or "asked") every single time, unless you really want to highlight something about the manner in which someone said something. you don't need to indicate the emotion behind every line unless it really isn't clear from the dialogue. "said" is so normal and ubiquitous that I promise it does not appear to the reader as repetitive.
more description is not necessarily better. don't mention what someone is wearing, what the furniture looks like, or even what the scenery is, unless there is some particular reason for doing so (e.g. there's symbolism in what this person is wearing; the furniture indicates something important about this person's taste or wealth; the reader is meant to connect an object in the scene with where it comes from; the scenery is particularly emotionally affecting to the characters in the scene; you're trying to slow down the pace during a dramatic bit; &c.)
it can be pretty obvious when someone is seeing a scene play out like a movie in their head and trying to describe that. but this is a prose medium. you are not writing a screenplay.
if there are two characters having an argument (about a personal conflict, or politics, or whatever), try not to make one of them "the right one" and the other one "the wrong one." it's boring
imagine someone asking you "why is that line here?" or "why did you include that detail?". you should always have an answer about why the work would be less effective without that line there. make everything pull its weight.
there is nothing wrong with just using an emotion word to state how someone feels. if you're going about it in some different way (mentioning their bodily reactions, for example), there should be some reason for it. is the character themself unaware of how they feel, only noting their own physical reactions? is the scene focalised through (meaning roughly, is it written from the POV of) someone else, who can only "read" the physical clues of the character's emotions? is this a character who is particularly susceptible to having strong physical reactions to things--someone who feels things very keenly? in my opinion, mentioning a physical reaction is a very strong, marked strategy that shouldn't be used every time.
a simile, metaphor, or otherwise imagistic or descriptive writing is not good just because it's beautiful. you might write a very beautiful sentence that nevertheless doesn't fit the mood of the scene, or whatever patterns of symbolism you've built up over the work as a whole. a metaphor is not just a container for meaning which, once unpacked, may be thrown away: the metaphor is the box and its contents. why specifically this metaphor for this thing? you should be able to answer that question. if a crescent moon has been "carved into"--why? are you trying to say something about consumption, violence, craftspersonship, "nature" versus "artifice," what? something can be very pretty and still need to be cut or revised. kill your darlings
basically, a lot of writing advice is going to tell you "more." more imagery, more description, more emotion, more "showing." this is good advice for anyone whose writing is particularly leaden (who isn't doing it on purpose), but it isn't always good advice for everyone. actually nothing is always good advice for everyone
"head hopping" isn't a real problem except for when it is. occasionally perspectives can switch in a way that's genuinely jarring and awkward, but that's not every perspective switch. look up "free indirect discourse"
read more, read widely, read lots of different genres and time periods, read translated works.
not only that, but read secondary literature about those works. if there's a text you particularly like, go on academia.org or something and try to find some scholarly articles that talk about some aspect of that work that was interesting to you. this will show you the kind of thing that readers can analyse when they read a work. for example, my writing is influenced just as much by Jane Austen scholarship as it is by Austen herself.
take all advice with a grain of salt, and don't trust anyone who tells you that their advice is the one and only key to good writing. there are 1000 different styles of writing and ethos behind those styles, and there are "trends" and "fashionable" ways of writing that change over time, as anyone who has read widely enough can tell you. don't listen to me even
look up what a comma splice is
look up what a vocative comma is
look up what a dangling modifier is
