Hello Italkian friend. There are many ways you can encourage someone making use of the written text. You can simply try these topics 1st - Greetings 2nd - Tell him/her how happy and excited you are about him/her taking the exam 3rd - Acknowledge his/her accomplishments so far 4th - Tell him/her what your expectations are 5th - Emphasize the importance of keeping calm 6th - Suggest a plan to study and keep track of things that must be in mind 7th - Finish saying how optimistic you are about his/her exam and just wish him/her good luck. Well, that is not really an academic suggestion. Just a personal one, based on my experience in encouraging my own students. Cheers!

to give him/her a direct instrument is the most helpful, like how to calculate a math problem...