I received a FINRA 8210 Letter

Hello everyone!!! I received a FINRA 8210 Letter, and frankly, I'm a bit at a loss. I understand that this letter is requesting information or documents for an investigation, but here's the problem - I'm not quite sure how to properly approach this. What documents do they typically request, and what's the best way to provide them? How long does the process usually take, and are there any pitfalls to watch out for? I've also heard that it's best to hire an attorney, but how do you know when you need one and how do you choose the right one to work with FINRA? I would like to hear advice from those who have already dealt with such requests and can tell me what to do next, so that everything goes as smoothly and without consequences as possible.