You can easily earn money by taking risky photos. When you you encounter a big monster in the hilly, it will be a fish-like sea monster. After the intermission sequence, take its picture and send it to the research center. You will get 2,000 credits for it. When you enter the factory, you will encounter another monster. Take its picture and send it to the research center for 2,500 credits. Take all the pictures of fish, animals, rats, and friends and all the people that roam in the street and bars and send them to the research center.