well firstly this type of writing is called persuasive writing which means you will need to use a range of persuasive linguistic devices, examples of these are:
- alliteration (where you begin a group of two or more words with the same letter, eg pink penguin)
- rhetorical questions (where you ask a question which can only be answered internally one way, it doesnt need to be answered- just there to sway the reader, eg do you want to be happy and healthy? the obvious answer to this is yes, but its so obvious it doesnt need to be stated.)
- lists (but in sentences, not spaced out below one another- use semi colons to seperate ideas ';' )
- colloquial language ( this is language that the target audience will relate to. so if writing to the teacher you need to write it formally and include phrases or words that they use often)
- opinion
- fact (VERY IMPORTANT to back up what your saying)
- emotive language (this is sentences, phrases or words, which provoke a strong emotion in the reader eg why would you let the destitute despair on your doorsteps? this provokes guilt in the reader)
- Command/ imperative (eg 'we don't have to put up with this!')
also link the paragraphs back to the point your making on the last sentence of every paragraph and include an introduction, a main body, and a conclusion
Good luck :) xxxx