If you are a Mobile Phone Repairer, a professional screw mat would be a best choice

If you don't have a screw mat, some daily used tools would recommend for you in the following steps.

The repair pad has a relatively high magnetic force, (as shown in the figure), which can effectively prevent small parts such as screws from sliding down, and a divided grid is used to store the screws or help you organize in any way you need.

If you can't remember how to reassemble, it's best to draw the same grid on a piece of paper and write out the type and steps of the screws.