First, decide what you’ll use your headlamp to accomplish. If you need to move through terrain with obstacles or wildlife, you’ll need more lumens — at least 300. If you’re a hunter or angler, you might want blue and green LED options.
Choose a design with a band that’s comfortable for your personal needs, including your head, skin, and hair. If you’re bouncing around or running, you might want a headlamp with a top strap.
Also, consider whether the battery duration is a match for your field hours. If not, you’ll need to decide if you want to carry extra batteries or a portable power bank to recharge the headlamp.