Canada

I'm not an English major, I write it kind of like a normal letter. You don't have to sweat the formatting too much, but here's what I usually do.

The subject line I put in a nutshell what I want: "Re-write (or Reject) Bill C-2: Canada shouldn't mirror the American Surveillance State" is what I went with.

"Hello [Mr./Mrs./M./Mme.] [Lastname], " is how you can start it of course with the appropriate choice for your MP.

You can start with polite formalities or an introduction if you don't want to start out of the gate with negativity. At some point before you finish the letter, you should state you are a resident of [neighborhood or town your MP is representing].

For negative items, in the second body paragraph opening you should clearly state what you are writing about. For me, it was, "I am writing today to express my disappointment in the first significant order of business being the Strong Borders Act (C-2), giving sweeping powers to the government to encroach upon Canadians' privacy and civil liberties." Positive items (thanking, commending, recommending, encouraging support for) you can do that in the same spot, at the beginning or anywhere between.

You should then state what you want, followed by the reasons why you want it. So here, write about the parts of the bill that feel like overreach and you want removed, like the mail inspection provisions, or digital data seizure provisions (Part 15). You can include what parts you think might be worth keeping or pursuing in another bill.

If you want to expand further, you can note what priorities you want your MP to put ahead (e.g. climate, affordability, economy, world affairs like Gaza and Ukraine, infrastucture, transport, etc.). Regardless of what they do with respect to a particular issue, MPs always want to know what their constituents find important to guide their future efforts.

If you want a follow-up you should state so in your correspondence. (Examples: "I would appreciate your follow-up", "I would appreciate a response", "Please get in touch at your best availability")

Lastly add your full name, address, postal code (to show you are from there) and optionally your phone number at the bottom.