My Advice
Guidance on asking for reference letters, including what makes for a good letter and how to approach the request.
How to write effective cold emails to professors about research opportunities, and how to position yourself to write better ones.
How to construct a credible NSERC application + a walkthrough of my own (successful, thank you) NSERC PGS application
Grad School Application Resources
No one person has a complete view of graduate admissions: decisions are made by individual professors or admissions committees at individual departments. The best anyone can offer is direct personal experience, things they heard, and common sense.
Shriram Krishnamurthi gives a detailed, frank, and incisive look at the PhD application process from the faculty side. There is also a detailed and more up-to-date written FAQ.
A document aimed at CMU students about applying to grad school. Note that the document is from 2014; CS has become more competitive since then.
A collection of statements of purpose from successful CS PhD applicants.
The UofT Department of Computer Science program to help applicants
An anonymous forum where you can search for specific programs to see what people say. Not necessarily reliable, but may be better than nothing.