What is the best way to troubleshoot a faulty starter motor in an Audi A4?

I am experiencing issues with my Audi A4 starter motor and I am not able to start my car. I have checked the battery and it seems to be fine. What could be causing this problem and how can I troubleshoot it?

Firstly, check the connections to the starter motor and make sure they are secure. If they are loose or corroded, this could be causing the issue. Also, check the condition of the starter relay and replace if necessary. The starter solenoid could also be faulty and will need to be replaced if this is the case.