There's nothing wrong about starting with Das Kapital. But most who are just learning about Marxism-Leninism will consider it too difficult and too hard to understand probably — I read the first 4 chapters of Das Kapital so far (then I had to delay further reading because I no longer had the time or energy, I should continue somewhen), and I had to really study it like some people study math, i. e. write out all the important information in points, draw some scheme to visualize it, etc., so not exactly an easy book to start with. I started with Imperialism As The Highest Stage Of Capitalism, it was much easier and still addressed important aspects.
There's nothing wrong about starting with Das Kapital. But most who are just learning about Marxism-Leninism will consider it too difficult and too hard to understand probably — I read the first 4 chapters of Das Kapital so far (then I had to delay further reading because I no longer had the time or energy, I should continue somewhen), and I had to really study it like some people study math, i. e. write out all the important information in points, draw some scheme to visualize it, etc., so not exactly an easy book to start with. I started with Imperialism As The Highest Stage Of Capitalism, it was much easier and still addressed important aspects.