Corporate website developement

Hi, I’m not new to wordpress, I have developed many plugins before and I know how the system works. I need to build a corporate website that will mostly be static except for a few sections like “our projects” with an ability to add photos to a project for example. It should’t look like a blog, but like a simple website, with a custom designed template from scratch, of course.
What would be the best practice to do so? How do you give the owner an ability to simply add projects and photos and stuff like that? How would it reflect in the theme development process? I don’t want the theme development process to be too complicated or long because it only has minor dynamic capabilities.
How do “they” usually do that?

Thanks!

——— EDIT ———

Oh, and the website will be RTL too, so I can’t really use any existing plugins cause they usually don’t really work well with RTL, from experience.