Based on your experience, What are the best advices for PhD students? & What are mistakes that should be avoided during PhD Journey to build a good future?.
First make sure they have done a thorough literature search and review so that they are not reinventing the wheel. Second always have a Plan B in case the original plan runs into problems.
Write the literature review after the research so that it is specific and keep your data confidential. Also, get external advice on statistics and analysis :)
constantly doing your research (do not postpone your -list to do- ), and write your activities daily: especially methods and result. in the end, it will be very helpful and you just need to compile as a dissertation and paper manuscript.