Dialogue punctuation = If you add a speech tag after dialogue, end the dialogue with a comma, and the first letter of the first word outside of quotations is lower case:
'This is an example,' she said.
Whereas if you put anything other than a speech tag after dialogue, i.e. paralinguistic description, then you end the dialogue with a period and the first letter of the first word outside of quotations is capitalised.
'This is an example of a hug.' She hugged the author.
Interrupting speech tags begin in lower case, end in a comma and the following dialogue begins with a lower-case letter:
'This is my example,' the author said, 'and it is simple.'
This can also be done with a period as such, and you just start the second part with a capital:
'This is my example,' the author said again. 'And it is just as simple.'
Speech tags can also come before dialogue. They must end in a comma and the dialogue must begin with a capital:
Gemma said, 'This is how you do it.'
British English uses single apostrophe around speech:
'Hello.'
American English uses double quotations:
"Hello."
Both are right.
Alas, there is no wriggle room in the domain of dialogue punctuation.