Understand the sector
Non-profit organizations are numerous, with many types of roles a geoscientist might fill depending on their skills and interests. As you explore employers, you will notice that many positions overlap with other sectors. Understanding the structure of non-profits and how non-profit careers are related to jobs in other sectors can be helpful as you begin navigating the job search. For example, if you are interested in working as a research scientist, you could explore both government laboratories and non-profit research institutes. If you'd like to go into science communication, you'll find opportunities that span the range of non-profits, universities, media outlets, government agencies, and more. Remember, the borders between sectors are fluid!
Similarly, if working for a mission-driven, non-profit organization is your goal, you can find a variety of positions that require geoscience-related skills. Explore communications, policy, science, and education roles at non-profits that match your interests to see where your skills might best fit. An exciting aspect of working for a non-profit is that employees tend to have a diverse range of responsibilities, especially in smaller organizations with fewer employees.
Volunteering and networking are great ways to learn the landscape of the non-profit sector and discover opportunities near you. The Idealist Guide to Nonprofit Careers for First-time Job Seekers is a useful general reference for learning about careers, volunteering, networking, job searching, and interviewing in the non-profit sector.