You will need
  • handle;
  • a sheet of paper;
  • envelope.
The first thing you need to consider to your friends is that the letters in the army visible. Therefore you should not blame the army orders, if your friend is very serious about service. If there are any problems, he'll tell you.
Support his friend. Tell them you are proud of him as his personal protector. Take a few funny photos of your friends in common. Prepare a comic "guardian of bullying".
Never write about the tragedies and bad news, forcing the situation. If you write that his girlfriend decided to end the relationship, the news could push the young man to rash steps that might have very serious consequences. And military censorship simply will not miss such a letter.
Positive must be more than stories about minor troubles. Try humorous questions about the army's orders to cheer up your friend and desire to answer a joke a joke.
Tell me about what is happening in your company in his absence, what do you do, what ideas and thoughts wander in your head, you can ask for advice in resolving any personal problems, or tell us about a curious case of mutual friends.
Plan how you will enjoy upon his return home, because you miss him very much.