Full Stop

Now then, this one's easy.

But, be aware:

These are two complete sentences and should therefore be distinguished with a separating full stop, or the addition of a connecting word after the comma   you can see why the guide to commas came first now.

Question Marks

Question marks - sheesh - are easy-peasy. They go at the end of any direct question or quote that includes a question:

Or

But, never use one in an indirect question scenario:

Or

Exclamation Mark

First and foremost, keep the '!' down to a minimal since too many suggests a childish style (it would stick out in a technical manual for starters). Use them sparingly and when you want to express some shock or strong feeling.

Or

Or

Note the difference between the following (the first, a statement; the second, an exclamation):

You can place an exclamation at the end of a sentence beginning with what or how, but it sticks out if you were to put it at the end of any other statement. That said, if a sentence is surprising or interrupting, it is allowed:

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