Talking about techniques, tools, ... often will lose the game for you. You need to be able to talk in business terms
to them, the explain the real benefits of doing agile.
What are they concerned about? Quality? Spending the money wisely? Time to market? Without knowing what the really want, how they define project success
you're merely shooting in the dark.
They might be concerned about issues that developers generally aren't interested in, such as governance
(which is good news because it is easier to govern agile projects
) or documentation
You might also need to make it explicit to them that traditional approaches aren't as effective as people hope. For example, writing a big requirements document up front
isn't such a good idea. They inherently know this, but might not know that they have better options.