How do you repair a fragment sentence?

Read your sentence out loud-- only what you wrote. Is it a complete sentence? Or, is the other half in the next sentence? Does the sentence have a subject and verb (actor and action)? Stop after each period-- if you have to ask "What then?" or "So what?" or "because what" after a period, you might have a sentence fragment.

Example:

Fragment: First sentence - He was going because. (because what?)

Fragment: Second sentence: He bought tickets.

Full sentence put together: He was going because he bought tickets.