How to test alcohol content with a hydrometer?

Hello there, I'm curious about the process of testing alcohol content using a hydrometer. Can you walk me through the steps, please? I'm particularly interested in understanding how to accurately measure the specific gravity of my brew and how that relates to the alcohol content. Additionally, what factors should I consider when taking readings to ensure accuracy? I'm new to this and would appreciate any tips or tricks you might have to offer. Thank you in advance for your help!