Easy Steps to Improve Your Writing
First of all, disclaimer: I am neither a professional/published author nor editor. I am however an avid reader and hobbyist dubbed Mr. Grammarly by friends. Said friends who also like writing and would ask me for feedback.
Fix your grammar. Probably the most important and easily forgotten step is to simply fix your grammar. This is especially horrendous where dialogue is involved. (Hint: Use a comma before opening quotations and all punctuation inside the closing quotation marks.) Your writing will never flow if your grammar is a sloppy mess. Even basic stuff, like consistent tenses, subject-verb agreements, and capitalization go a long way. Do take five minutes to edit your writing by following the squiggly lines.
Still related to dialogue, make your characters speak like ideal real people. What I mean is that they should sound like something you would want to say or hear someone say. Unless it's important to the scene/plot, get rid of stutters, trendy slang, or even swearing. On the other extreme, make them sound like people with that characteristic would. Don't write young girls talking like old men, or a chinese monk talking like an american teenage boy.
Unless it's crucial to the plot, you don't want an exposition dump of more than five sentences. You're writing a story, not an essay.
Don't worry about cliches. Cliches are cliches for a reason: they work. A lot of people seem to try and avoid cliches no matter what and end up reinventing the wheel. It's not what happen that matters, it's how it happens.
Slow your scenes down. Most (amateur) writers rush through scenes, stating them rather than actually describing the scene. We get it, Jack fought Bill, but how exactly did the fight go?
Stick to one point of view. If you're writing in third person, stick to third person. If you're writing in first person, stick to first person. It's fine if you change perspectives/narrators in the next chapter, but do stick to just one POV.
Unless it's a phone number or address or similar, all numbers below twenty should be spelled out.
Read books. You can't write well without reading a lot. It's actually astounding how many people tell me they want to write but haven't finished reading a proper book in the last two years. If you have a favourite author, try to find out what exactly works about the writing and emulate it. The same way people try to emulate their favourite athlete or musician, you should try to emulate your favourite author. Even if the technique doesn't work for you, you'll discover new things about your writing.
Hope this helps!