I finished reading Harry Potter.

2. I prefer don't go.

I prefer not to go.

3. I don't like read the newspaper.

I don't like reading the newspaper. OR I don't like to read the newspaper (This doesn't sound so good).

4. My problem is to pay.

My problem is paying.

5. Before to start, ...

Before starting, ...

6. It's better don't take the car.

It's better not to take the car.

7. I prefer don't speak about it.

I prefer not to speak about it.

8. Laura enjoys to be alone sometimes.

Laura enjoys being alone sometimes.

9. I wouldn't like being in his shoes.

I wouldn't like to be in his shoes.

10. I don't mind to help.

 I don't mind helping.