I would recommend in first teaching the very basics that are used in almost every language, but doing so without a language. Outline all the basic concepts If-Else If-Else, Loops, Classes, Variable Types, Structures, etc. Everything that is the foundation of most languages. Then move onto really understanding Boolean, comparisons and complex AND OR statements, to get the feeling on what the outcomes are for more complex statements.
By doing it this way he will understand the concepts of programming and have a much easier time stepping into languages, from there its just learning the intricate details of the languages, its functions, and syntax.