my wife practiced online questions, she bought a package for 24 dollars. For me I had only 3 days (after work) to study and I went through the official book "Discover Canada". I had three simulation tests from my wife's package and I got 18/20, 16/20 and 19/20. That means the online test is more difficult than the actual test.
I started by the questions on the end the book. All those questions are answered on page 100 on the following guideline from Manitoba
http://citizenshipcounts.ca/content/pdf/citizenship-guide-newcomers-manitoba-self-study.pdf
After I practiced the questions and answers, I went through the official book fast reading and I wrote my own questions and answers. Only subjects and headlines.
3 days are more than enough to pass the test.
If your English is good, then you can eliminate wrong answers which don't make any sense. Other people said its difficult.