One of the best ways into a new area is if you can find a well written PhD or MSc thesis in it. Finding that isn't always easy, but if they are well done the background introductory material will be approachable and much more complete than a paper, and the bibliography should be useful.
You make assumptions, just when you learned your first language. Then you check if everything makes sense. If it does, then probably your assumptions were correct.
Posted this paper long ago on HN too. It is probably the most consistent information on how to read a paper.
The sciencemag article is nice read after this paper though, since there's a couple of small trips&tricks that is not in that paper (such as the emotional side of reading a paper, how to go on when you actually don't understand something/jargons, when to give up/look for better paper, etc)
Thanks for this! The format of the interview is clearly not aimed at clarifying how to (seriously) read scientific papers, with contradicting views among the interviewees.