Gifts:
Supernatural
TAXI
X-Men
I don't warn for content from canon.
For example, in Buffy the Vampire Slayer you may expect death of minor characters without warning, references to the deaths of Buffy, Joyce and Tara, references to mutilation, references to cheating, references to addiction, references to bunnies, and so on and so forth.
If there is content that you would not normally expect from canon, I warn to the best of my ability. Feel free to ask me about content, or ask me to add warnings if you found them lacking.
Sometimes I may warn for content you would expect from canon, if I find that it's more graphic or affecting or for any reasons needs a warning. This does not mean that I will always warn for that type of content in all my fics.