Try to be in and create an environment where you are constantly stimulated by curiosity. Exposure to top-notch science may be the quickest way to achieve this. Scientific American, National Geographic, Discovery Channel, Nature podcast, Science podcast, reading your favorite books, attending scientific meetings, talking about science with friends, watching Youtube, etc. Sometimes people may not share your ideas and thoughts or even reject them, but don't be afraid to make mistakes, trust your curiosity and go for it. Here you can read my experiences [Sorry it's only available in Japanese].
Campbell Biology is an excellent textbook for a broad study of biology in general. I highly recommend reading it while you are enrolled in undergraduate or graduate school. I also recommend you to try finding problems or knowledge that are not well-written in the text, because that is the way how you can train yourself as a scientist.
Other recommended books:
Read as many books as you can. Chemistry, Physics, Cognitive science, Computer Science,
etc. Especially, History of Science will help you understand how scientists were often trapped in comon sense at each era.
The Lady Tasting Tea
The Theory That Would Not Die
Get prepared for interacting with scientists from all over the world. If you are not English native speaker, spend time on learning English. For those who never lived abroad alone, don't hesitate to jump in and join us. I also have experiences of living abroad (Canada, Unted States), and
many of our lab members are from abroad. I'm also collaborating with researchers from various countries, including UK, USA, China, Taiwan, Denmark and so on. I'm also proud to tell you that Japan has been ranked as the safest country in the world.
For admission policy for international students can be found here. We have financial support to cover tuition fees, and all the students will get their laptop computer for free!
Please don't hesitate to contact me if you are interested in joining our group: 
EN/JP
IRIE lab. -
