What’re you telling me? What are you trying to say?
This is something of a bugbear for intermediate students. I would like to tell you how to do it correctly. The problem is the structure. It is impossible to use these words correctly if you do use (or not use) the correct prepositions first. As you can see “tell” is never followed immediately by a preposition. And “say” doesn’t always have the complement.
We can go through the following practice.