The phrase "careful preparation" means taking the time and effort to plan and get ready for something in a thoughtful and thorough way. Full definition
She calls for more careful preparation of teachers, more time for them to collaborate, and more opportunities to teach in ways that are interesting and alive. (educationnext.org)
Their professional training and judgment, combined with careful preparation assures this. (sea-quest-kayak.com)
«The interview is crucial for your career» and requires careful preparation, she warned. (sciencemag.org)