When a person wants to postulate something, what are the rules and best practices he can adhere too?
How should the idea one is trying to express be formulated?
If you want to use formal logic as inspiration, there are three appropriate ways to use postulates:
First, you can postulate something, show that accepting that postulate leads to an impossibility, and thus show the postulate is false.
Second, you can postulate something, draw a conclusion, then postulate the opposite, draw the same conclusion, and thus show the conclusion is sure.
Third, you can make a postulate, and draw a conclusion, and thus show that if your postulate were true, your conclusion would be as well.
Any idea you want to postulate should be proposed in such a way as to make criticism as easy as possible so that it can be eliminated if it is wrong. This leads to many methodological constraints as explained in "Logic of Scientific Discovery" by Karl Popper. For example, an idea should have implications for some issue beyond the problem it was originally invented to solve partly because if it has no such implications there is no way to eliminate it if it is wrong. For more details of the rules Popper proposed see
and references therein.