Even if you’re not writing an action-packed, fast-paced book, a smooth and quick flow to your words is very important. You want your book to “carry” your reader along, which means minimizing places where the reader might get bogged down or tripped up. This is why editing is important, but not just in terms of spelling and grammar. It’s also about word choice and streamlining. Get the most “bang for your buck” for the words you use.
Sometimes more words that aren’t exactly needed are used for drama or emphasis, but oftentimes, they are just redundant. When that’s the case, you want to trim those down to make everything smooth. It’s just like taking a file to a ragged fingernail.
1) When someone shouts or yells something, you almost never need to add “out.” They don’t need to shout out or yell out; they can just shout or yell. Sometimes “call out” is better than just “call,” but always read it aloud to yourself and see if you need it.
2) You don’t ever enter out of something, so you don’t need to write “entered inside.” They just entered.
3) Sometimes, there’s an assumption that readers will make. If you say someone shrugged, they will assume it was with shoulders. If you say ‘point,’ they will assume it was a finger. Only if it’s NOT done the assumed way–they pointed with a toe–should you put it in. Don’t write, “pointed with a finger” or “shrugged their shoulders.”
4) Do people every actually nod with anything but their heads? Or clap with their hands apart? “Clapped their hands together” is usually unnecessary.
5) If there are only two people in the scene, one character doesn’t need “said to the other person/name” written. They can just have it said.
6) Unless you have telepathy in your book, you don’t need to write “to herself/himself/myself” after a “he/she thought.”
This list is not exhaustive, but it’s some of the most common examples I’ve come across over the years. When you’re doing your self-editing, always keep an eye out for things that are redundant, excessive, or so obvious as to be unnecessary.