Tips for assisting a person who uses a letter board

Find out:

If they have written instructions on how they communicate
How the person communicates yes and no
If they have important gestures and body language that you should know
Where they keep their board and if you can get it for them
Where they want you to sit when facilitating their communication
How they point to items on their board
If they want you to hold their board in place so it stays in place when they are pointing to items