One of the simplest things you can do to improve your writing is to avoid the passive voice. However, there can be a time and a place for it. The time and place for the passive voice is when you are writing dialouge.
The reason it's OK to use passive tense in dialogue is because people often talk that way. Meanwhile, the way authors describe a scene, a person's appearance or a what somebody thinks of a situation is not the way most people talk. But when you describe those things, you need to find a way to grab the reader's attention and get them to visualize things.
When you have a typical conversation, you should have the other person's attention. So when you write a conversation, your reader should understand that the people talking to each other have each other's attention. (Of course, that's not always the case, whether it's real life or when you write a conversation.) But it's OK to have your characters use the passive voice when they talk. You don't want to overdo it (unless you have a character who talks a certain way) but you can get away with it as a writer.
But when you write narration, your task is to capture the reader's attention. Some people might talk in passive tense, but that doesn't mean those people will read it. Passive voice causes readers to drift away and your job is to keep your reader's attention.
Think of it this way: Narration and dialogue are different. Narration means describing action, scenery, objects or feelings. Active voice does the best job illustrating that and allowing your readers to visualize or relate to it. Dialogue is about how your characters talk and their words do the best job of that. The dialogue itself should be enough to convey to readers how the characters talks. You can add to that with brief narration about the character's movement or posture, but the words the character says provide a lot.
If you are looking for the best way to improve your writing, eliminating the passive voice is a good first step. Just remember that your focus should be on your narration first and your dialogue second.