The first step towards critical reading is to keep your purpose in mind when you read. Don't let the arguments distract you from your reading agenda.
Previewing or prereading can help focus your thoughts. Skim headings and article abstracts, perhaps look at the first line of each paragraph and the conclusion.
Unlike journal articles and scholarly books, the majority of information found with a Google search has not been peer reviewed, unlike journal articles and most scholarly books found via library databases. It is therefore very important that you read these writings critically and objectively.
When you are looking at resources (particularly from a Google search) keep a critical focus. Use the CRAAP method to evaluate your information:
Currency: How old is the material? Is it current enough for your topic?
Reliability: Is there reliable evidence to support the author's contentions?What is the perspective of the writer? Is it balanced?
Authoritativeness: Who are the authors of this piece? What are their credentials?
Accuracy: Are the arguments logical?Has the material been reviewed or refereed? Is the material supported by evidence?
Purpose: Is this fact or opinion? Is it biased? Is the author trying to sell you something? Or persuade you?
You should have some specific questions in mind as you read, which will help you deal with the material actively.
Keeping a list of questions in mind will sharpen your analytical skills and help you keep an objective outlook. These sample questions are aimed at eliciting a criticism of experimental methodology:
What were the authors trying to discover?
Why is this piece of research important?
What was measured?
How was the data collected?
What were the results?
What do the authors conclude and to what do they attribute their findings?
Can you accept the findings as true?
How can you apply these findings to your own work?
These questions should form the basis of your literature review. If you take comprehensive notes in your own words you will have done the hard work before you start to write.
Image sources: Reading glasses. Evan-Amos. Public domain. Wikimedia Commons; Ludwigs2, Question Mark. CC BY-SA 3.0. Wikimedia Commons.