Avoid the Comma Splice

Part 3 of a 3-part series on the usage rules for commas
To avoid looking unlettered, master Rule Three:

Never use commas to splice together separate sentences.

Grammarians call an infraction of the rule a "comma splice." 

Here's an example:

Thanks for registering for FACE, check your email for confirmation.

What's the right way to state this? Chop it in two:

Thanks for registering for FACE. Check your email for confirmation.

Seem too choppy? You could use an em-dash:

Thanks for registering for FACE—check your email for confirmation. 

Or, at last resort, a semi-colon:

Thanks for registering for FACE; check your email for confirmation.

Marketers most often introduce comma splices when linking separate, but related, ideas:

Admission to FACE Expo is free, however you must pay to attend the conference sessions.

Grammarians consider the adverb however too "weak," however, to separate the ideas. Only a period, em-dash or semi-colon will do:

Admission to FACE Expo is free. However, you must pay to attend the conference sessions.

Admission to FACE Expo is free—however, you must pay to attend the conference sessions.

Admission to FACE Expo is free; however, you must pay to attend the conference sessions.