Be determined to do-it-yourself? You must make sure that you can prepare all the documents as required by Citizenship & Immigration Canada. Precondition: 1.you have all the necessary official information about the application (you can download all information from websites: www.cic.gc.ca and www.canada.org.hk.)2. you have the ability to prepare the documents accordingly(Particularly, language skill). why so many are applying by the agents?Reason 1: many of them do not believe they can do it by themselves because everything is in English. Suppose that we are applying for Permanent Residence Visa to Shanghai and everything is in Chinese,I am sure that everyone will DIY and the agents can't make a penny. Reason 2: they believe the professional agents with experiences can avoid some mistakes and make up for some shortcomings.
you still want to do it yourself?
If so, you are really a step ahead of the others.
I am doing application myself. Everything is going well. Let's do it.