When students simplify algebra problems, they often make some common mistakes. Here are a few to watch out for:

1. Not Combining Like Terms: Remember to put similar terms together. For example, if you have $3x + 2x$, don't forget to combine them into $5x$.

2. Getting Distribution Wrong: Be careful when distributing. If you see $2(x + 3)$, make sure to multiply both parts. This gives you $2x + 6$.

3. Missing Negative Signs: Be on the lookout for negative signs! When you see $-(x - 4)$, remember it turns into $-x + 4$.

4. Cancelling Too Soon: You can only cancel factors, not just any part of the expression! For example, in $\frac{2x^2}{2x}$, you can cancel to get $x$, but don't cancel like that with $x + 1$.

Keep these tips in mind, and you'll feel more confident when simplifying!