Causing someone to believe something requires either a chain of logic or a set of evidence. If to believe proposition p, someone also has to believe e.g,. proposition p1-p3 and the probability of convincing them of each of one p1-p3 is 66%, then the proabilty you will be able to convince them of p is only 30%! Before you embark on convincing someone of something using reason or evidence, think about the probability of your success. Is it really worth it? Perhaps it is more efficient simply to make them like or fear you and agree with you for those reasons. If you go with that approach, try the techniques described here.
Why persuasion by evidence/reason is hard?