1. Be interpersonal
Form genuine, close relationships with a range of individuals who can go in touch on different points of your experience/character
2. Have a range of letters that show adaptability and versatility
They should all speak on different things that connect to your main career. These letters can come from former clients, employers, colleagues, mentors, etc.
3. Give your recommenders an idea of what you want them to specifically touch on
How do you know them? What has your relationship been like? How have you worked with them? Have they benefited from your work?