Imagine that a friend of yours sent you a letter asking for your advice as he/she and his/her parents disagree about what university he/she should study
at. write a letter giving your friend some advice according to the plan:
plan
introduction
paragraph 1: greeting; mention receiving your friend`s letter; express sympathy.
main body
paragraph 2,3: give your advice and the reasons of it.
paragraph 4: closing remarks: end the letter offering some encouragement/wishing the person good luck;
start like this:
dear
i`ve just got your letter and think i can you.
best wishes,