Low Level Design Part 1: Reading and Gathering Information

Start out your document writing day 1 with a long list of open questions. As you read documents, you should slowly grow a longer and longer list of open questions. Maintain this list and keep adding to it while you write the doc. Questions are often more important than answers as they represent unknowns you need to disambiguate.

You will need to ask people for most of your open questions. This is okay and most engineers are very happy to answer such questions. In general, people will feel more complimented rather than inconvenienced when their expertise is requested. If you can't find an answer to something and don't know who to ask, ask your manager or a senior engineer on your team.

What if no one knows in your team? Formulate your question into something brief and meaningful and post it in your org or company-wide chat. If your question is technical, ask it as a stack overflow question and link it in the chat along with your question.

Link to everything as hyperlinks in the document, or in the appendix if it doesn't fit somewhere. Every document you ever read when putting together the LLD should be somewhere in the appendix. This will save you an enormous amount of time later when you're putting together these components. This can also make it easier for other developers to work using your LLD so they won't have to ask you as many questions.

Keep an open line of communication with your PM and the customer. You will have a lot of questions for them. You may even want to set up a weekly sync so that you can make your that your ideas of how the software will work match theirs.