Answer:
Look into what courses you need to do to follow a career in environmental protection, or contact good zoos - the kind that preserve and breed endangered species for eventual return to the wild - and ask them what qualifications you would need to work there. Look at endangered species in your country and what projects are being run to help them, and see if you can get involved, even if it’s something unglamorous like stuffing leaflets into envelopes.
Getting professional education in certain relevant fields like Biological Sciences; Environmental Sciences; Political Sciences & International Politics; Mass Communications and International Media and then pursue your career accordingly.
Joining a non-profit organization/non-governmental organization serving the purpose (like WWF etc.). Even if as a volunteer — this will satisfy your passion as well as groom you in the best possible manner at this stage.
Arranging and organizing Co-curricular and Extra-curricular activities in this context and/or forming a Student's Society with this purpose in your school/college. In this way, you can not only get more relevant and practical ideas from your fellows but will also be able to leave a legacy behind.
Discussing this with your parents/guardians in relation to their contribution and input for this beautiful intent of yours (both in the sense of money and permissions).
Learning about any species which are vulnerable near you and help educate others as to ‘why these species need protection’ and ‘why they need that protection now’ (courtesy Jenny Swainston).