Caveat: my training is in control system,s not computer science. I assume these types of papers to be similar enough that the following will be useful.
I have heard that advice before, but I generally disagree. Unless you are doing a literature search, reading the references is a waste of time. And most conclusions aren't really worth reading either. They typically read as though the author has completely exhausted themselves by writing the rest of the paper, and simply restart the last paragraph of the introduction in new words.
If you are trying to get up to speed on a new field, a good introduction can really help with you reference search.
Part of "how to read a paper" depends on what you are trying to do. If it's a seminal paper that are are just going to read, that is a very different thing from reading a paper in search of a solution (or trying to figure out of your idea is novel).
In this second case, your main task is to decide if the paper is even worth reading. IMO, this takes a lot practice. Fully reading a paper to the extent you really understand it can be extremely time consuming. It's important to be willing to throw out the paper if at any point (no matter how much time you've put into it) it becomes clear it doesn't work for you.
I will generally skim the abstract and/or the last two paragraphs (or so) of the introduction. If it still sounds promising I look through the next section or two, which are usually some kind of "problem setup" and "proposed solution scheme". I skip things I don't immediately understand. If my interest is still piqued, I look for the results section where the plots are (if it's a practical paper). If I'm still interested, I go back to Section II and start reading more carefully. I'll spend more time with tricky math, but not too much. Save staring at the same four equations for two hours for at least the third pass.
Oh, and if a paper is tricky (for me) and seems worth my time, printing it out single sided and laying the pages out side by side on my desk can be really helpful.