You won't die if you combine poorly. All you'll get is bloating and gas, big deal. Why not try out what works for you and what doesn't? With some self-experimentation you'll learn very fast what your body can deal with and what it cannot deal with.
I don't think it's a good idea to want to "do it right". There's no right and wrong about diet, your body is unique and what works for you doesn't work for someone else. Plus, this will change over time. I used to be able to eat big mixed fruit salads with many different fruits, and now I can't anymore. On the other hand, I have no problem mixing sugar with fat or fruit with veggies.
Why don't you want to invent your own rules? If you like combining fruit and nuts and have no problem with it, who cares if others think it's bad?
My opinion: there is no right path.