Tense and sequence

Consistency across a passage.

Staying consistent

Pick a tense and keep it unless the time genuinely shifts. Unmotivated switching between past and present is one of the most common errors in long writing.

Use past perfect for something before another past event.
Conditionals: if I were, not if I was, for hypotheticals.

Reported speech

Tenses usually shift back one step when reporting: he said he was tired. Failing to shift reads as quotation without quotation marks.