This may be a personal pet peeve, but have you noticed how often in stories the word 'it' is used? I'm not talking about how the word properly acts as a pronoun but where 'it' is used as a vague noun. Examples: “It was snowing outside.” “It was five in the afternoon.”
What is 'it' in the preceding sentences? If the writer is speaking about the weather, can he not just state, “Snow fell...” or if referring to time, “I saw the clock read five in the afternoon.”
Again, maybe 'it's' just me, but I see this a lot and not liking 'it', causes me to catch 'it' every time I read 'it'. Unfortunately, sometimes 'it' can't be avoided. I've discovered this in my Alpha rewrite. Sometimes, there's just no getting around 'it'.
However, I always try to rewrite the sentence so the words can better describe whatever 'it' is. I think the paragraph flows better, adds more context or description or action. When reading, I see 'it' in many instances and I always think how I could rewrite that particular sentence.
There are several grammar glitches I see in popular authors' work. I wonder how they get away with, uh, it. A glaring example might be, “He was the person that committed the murder.” I remember my good friend Mary correcting me many years ago when I committed that murder, er, error. Things are 'that', people are 'who'. “He was the person who committed the murder.”
Another incorrect use of grammar, also caught and noted by Mary, is one that is used extensively by every diet, vitamin, exercise, etc. commercial. They all talk about wanting us to live a more healthy lifestyle. A lifestyle is a thing. Things cannot be healthy. People or living entities can be healthy or unhealthy. You can live a more healthful lifestyle and be healthy by so doing.
Who and Whom are two other biggies not so commonly misused except in speaking.
Another common error I often catch myself making and try very hard to correct myself before committing it is the difference between 'well' and 'good'. “He plays the trumpet good.” is incorrect as is, “You did very good today.” Again, I thank Mary for noting that one when I spoke to taekwondo classes years ago. Good is the adjective, well is the adverb. “He did a good job.” but, “He did the job well.”
One common problem I run into when writing is trying to not end a sentence in a preposition. The difficulty lies in the fact that you must write how people speak. If the character is very formal, he may say, “From where are you coming?” Which is proper and will read well. (or will read good?) However, if you say that on the street, some people may look at you in a strange way. Most people say, “Where are you coming from?” Granted, not technically correct grammar, but it's how most people speak. Stay consistent with your character's speech patterns. I'd like to warn you not to overdo it, but unfortunately I've stumbled across a few short stories where the protagonist, usually a teen or twenty-something very rural girl will narrate or do the most speaking and will speak in a countrified, backwoods type speech. I'm sure the story is a great one and I know my latest role is to push short stories, but again, personal pet peeve, I don't read past paragraph two when I run across them. I'm sorry, they bother me. I know the type of speech pattern adds flavor or spice, but, it irritates my senses to constantly have to interpret.
Just keep a tight hold on your grammar is all I'm suggesting. I'm sure my editor, when reading my stories during the rewrite/edit phase, will probably cringe at some of my grammar (hey, I'm not perfect), but maybe during the process, I'll learn some rules and be better at, uh, it, the next time around.