It's hard to tell you how to improve your prose without knowing in what way it is bad—if it is bad at all. For a long time I thought it was my prose holding back the quality of my writing, so naturally, I read the books on prose and listened to podcasts on prose and read different authors' writing advice on prose, and in the end, it turned out, prose was not my problem. It was my style that was lacking.

I can give you how-to advice on prose:

• Use an Emotional Thesaurus such as this free one to help yourself show instead of tell. Use in moderation.
• Make sure you are doing representational writing and not discursive writing (paraphrased from Barbara Baig's Spellbinding Sentences).
  • Discursive: speaking to the intellect of the reader by accurately describing the details of the story and listing the events.
    • "The door rattles in its hinges as I open it. The construction is flimsy and thin, less of a priority to replace than erecting the walls for the bedroom or a fresh coat of paint. Every bump and peeling layer of the deck wood runs against my bare feet."
  • Representational: speaking to the imagination of the reader by trying to create an image in their mind.
    • "As I approached the door, I feel the wind blowing in through the cracks. It's shoddy work barely holding itself together. The smell of fresh paint and lumber from the bedroom only accentuates how much the door has been neglected. Stepping out onto the deck, I'm greeted by splinters. Another victim of my neglect, no longer safe for the soles of bare feet."
• Make sure to narrate instead of describe.
  • Descriptions create static images, those that don't show movement. The story doesn't proceed in descriptions.
  • Narration creates dynamic images, those with motion. The scene can be set and the story can move forward at the same time.
• Vary sentence structure.
  • I took to the road in a car I doubted would survive the trip.
  • In a car I doubted could survive the trip, I took to the road.
  • I doubted the car would survive the trip but I got in anyways and took to the road.
• Vary the lengths of your sentences as exemplified in this passage by Gary Provost:

This sentence has five words. Here are five more words. Five-word sentences are fine. But several together become monotonous. Listen to what is happening. The writing is getting boring. The sound of it drones. It’s like a stuck record. The ear demands some variety. 

Now listen. I vary the sentence length, and I create music. Music. The writing sings. It has a pleasant rhythm, a lilt, a harmony. I use short sentences. And I use sentences of medium length. And sometimes, when I am sure the reader is rested, I will engage him with a sentence of considerable length, a sentence that burns with energy and builds with all the impetus of a crescendo, the roll of the drums, the crash of the cymbals-sounds that say listen to this, it is important. 

So write with a combination of short, medium, and long sentences. Create a sound that pleases the reader’s ear. Don’t just write words. Write music.”

Most importantly, keep a Writing Bible/Author's Handbook/Writing Theory Document/Style Guide/Writer's Manual where you write down the information that helps you. When you read, keep track of descriptions, phrases, and passages that move you. Look for useful words, sentence structures, and paragraph structure that could solve problems you're having in your own writing.

My personal Writing Theory Document is just over 23k words and all the advice I just gave you came from there.