1: Avoid cleaning rare Kennedy half dollars.

2: Don't store coins in acidic holders.

3: Be cautious of overgrading coins.

4: Keep an eye out for counterfeit coins.

5: Don't disregard the coin's condition.

6: Handle coins with care to avoid damage.

7: Research before purchasing valuable coins.

8: Don't ignore the market trends.

9: Consult with experts for accurate appraisals.