Hi there, and welcome.
Yes, there absolutely is. Your aim should be to make them as intuitive as possible (and requiring the lowest possible cognitive load). For links that means underlining them, colouring them blue (or at least a different colour from the rest of your text) and changing their colour when the state changes.
For buttons, read up about the Von Restorff (or isolation) effect.
You’ve actually done all of this really well on your site. Your text is also clear and easy to read (although I can’t read it due to the language). I don’t think any of those things need work.
But as you say, you’re wasting valuable real estate with your header image. It looks great, but your site looks like a blog, not a sales page. If the primary CTA is those buttons, make them the first thing I see.