When in the past I've picked up a reference manual or something of the sort I'd go slowly, lookup every word I didn't understand and started experimenting as soon as possible.

But that is quite time consuming and intense. I've been considering skimming through the whole things to get kind of a big picture of what the thing is and where I'm going and then going back a second time to catch then the details and experiment.

Any other ideas? How do you tackle learning something new and complicated?

(ps. the complicated thing for me right now is kernel development, including writing proper C)