When changing improper fractions to mixed numbers (or the other way around), there are some common mistakes to watch out for:

1. Don't Forget to Simplify: Always make your answers as simple as possible. For example, when you change $9/4$ to a mixed number, it should be $2\frac{1}{4}$, not $2\frac{4}{9}$.

2. Pay Attention to Whole Numbers: Mixed numbers have a whole number part too. So, when you change $7/3$, it should be $2\frac{1}{3}$, not just $2.333$.

3. Watch Your Division: Make sure you’re dividing the right way. Divide the top number (numerator) by the bottom number (denominator) and don’t forget the remainder.

If you steer clear of these mistakes, you will feel more confident when making these conversions!