What should the photographer prepare for shooting outside, such as some small equipment. And those very meticulous preparations! Please advise if there are experts. Thank you.

Bring as many reflectors as possible, as well as reflective umbrellas, which can also prevent rain and sun.

External lights, if any. If not, buy an external flash, a soft light cover (usually attached), a tripod and a flasher, which can be equivalent to multiple small lights.

It must be helpful to bring more assistants.

If you have a car, it's natural and convenient. If you don't, find some lighter equipment and props.

Models certainly need makeup artists, napkins and the like.