For simple if-else statements, pay attention to the order of the if and else clauses, especially if they process a lot of errors. Make sure the nominal case is clear.

For if-then-else chains and case statements, choose an order that maximizes read-ability.

To trap errors, use the default clause in a case statement or the last else in a chain of if-then-else statements.

All control constructs are not created equal. Choose the control construct that's most appropriate for each section of code.