Conventions for punctuating dialogue are different in the USA; what I’m suggesting here only applies to UK publications.
Placing the quote marks
The spoken text is enclosed within quote marks. This includes any final punctuation.
‘Hi, there. My name is Mary. I am your tour guide for today.’
The punctuation for the spoken text as ‘as normal’ except in these cases:
People talk in fragmented ways – not necessarily full grammatically correct sentences. How you punctuate this is up to you! Compare these two:
The second version tries to convey a passing of time while Kate listens to what is being said to her on the phone.
Most people contract words when they speak, so this should be mirrored in your dialogue. An apostrophe is used to indicate missing letters.