Just a quick note today touching on dialogue tags ... or, for my American friends, dialog tags ... because I believe it is the #1 thing on my most-fixed list.
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On to punctuation. I'm only going to address ONE simple point. If you want to know more, just ask.

Don't do this: "Hello there." she said.
... Do this: "Hello there," she said.
or Do this: "Hello there." She smiled and waved.

And another thing:

Don't be afraid of the word "said"; 
... Do try other good words you can use, in addition to "said" ... have you tried "replied", "asked", "shouted", "whispered", "muttered", etc