Written confirmation email after every phone call. Cheapest insurance there is.

Bring a list. Embarrassment makes everyone forget things, including you.

File early. The window is shorter than people think and it starts at the transaction.

Photograph everything before you open it. Ten seconds, settles most disputes.

Test one thing at a time. It feels slower and it is the only way to learn anything.

Ask for the longer appointment slot. Ten minutes is not enough for a complex history and pretending otherwise wastes both your time.