Don't tell me what your character saw, show me.
Buster peeked around the corner of the sofa and spotted Garagee resting on dad's legs. Buster couldn't help smiling. Or was that a sneer?
His muscles taunt, his steps powerful, Buster strutted through his kingdom, his nails occasionally snagging on the carpet. He rounded the corner of the sofa and spotted his unsuspecting victim lying across dad's legs. "Here I come, Miss Garagee, ready or not."
Today's tip is just one bridge to a deeper narrator. If you're excited about your manuscript yet know there's more you can do to enrich the prose, go through and eliminate anything that takes your reader out of your protagonist's head. Search for statements like: he thought, she knew, he watched, and rephrase to show the result of their actions. Instead of telling me he watched, show me what he saw. Instead of telling me what he thought, show me his thoughts.
He thought the pain in his chest had ripped a hole through him.
Horrendous pain burrowed through his chest; his legs crumbled.
She heard the loud boom and knew it was a gun.
A gunshot rang out, and Julie pressed her hands to her ears. Oh shit -- my eardrums are busted!
And, as I've said many times before, remember the best part of writing a book is revising. It's like renovating your house instead building a new one.