Sorry for the late reply, sweetie. I gave it a quick read and here's my tips:
Punctuation matters. If a sentence begins or ends with a given name it should always be followed up by a komma. "Jack, you're being a real son of an arse right now!" -- "I don't think you mean any of that, Mark."
Also a sentence that is built out of two sentences, should be split by a komma. Ex: He knew it was gettin' late, yet ge kept waiting nonetheless.
A conversation that is ongoing, should be ended with a komma to signify that one sentence is followed by a next, unless the statement is a question or exclamation. Ex: "you didn't even see me there,"
"That's not true. You were just as blind as a bat!" "Was I?" A spoken sentence only ends with a period if no answer is expected. Ex: "you're just An idiot. End of discussion."
Despite most teachers saying otherwise, add as many details as possible. Not only dies it give the illusion of lengthening the story, it enriches the story, environments and characters. Ex: the ball is red. -- The ball held a crimson shade, with soft rounded shadows leaning over it's circular shape.
I hope this helps. ^ v ^