Depends on the type of paper.
If it's in the model of a STEM style paper, then read abstract, read intro + conclusion, see if findings are relevant or interesting or significant. If they are, read the whole paper while recreating the logic/experiment/problem in your head. Question, question, question. Actively read and constantly question the findings or nature of the experiment.
If it's in the model of a humanities or argumentative paper, then read the abstract with a focus on the central thesis or argument, it should be clearly stated. If it's not, then the paper might be poorly written, or too vague to be very useful. If it is, then judge if it's relevant or interesting or significant. If it is, read the intro section. Decide if you should continue reading. When you read the rest of the paper, always refer back to the argument and thesis in your head (which should be clearly stated and summarized in the intro section). Actively question the logic and steps of the argument, evidence, analysis. Assume they will address counterarguments; if they don't, be savage and see if pulling on the thread of a counterargument undoes the whole logic of the paper. Take notes but don't just copy, note your reactions to the paper.