1. INFORMAL LETTER

2. STRUCTURE
(YOUR) ADRESS AND DATE: Some people prefer to leave the adress and date out. However, you can include them in the right hand corner.
GREETING: Dear Laura, Hi! , Hello Laura, etc.
BODY: Content of the letter.
CLOSING: Love, Lots of love, Best wishes, etc. (Always followed by a comma)
POST SCRIPT: A short message after the closing. Use it to write something that you have forgotten in the body of the letter.
SIGNATURE

4. TIPS
You can use the first paragraph (after the greeting) to tell your friend about your life and ask him/her about theirs.
Use of contractions
Use of exclamations marks at the end of short expressions to show strong feelings or surprise : Brilliant news! Congratulations! (Don't use them too much)
Use of questions. It shows that you include the recipient in your letter and expect an answer from him/her.

6. LINKS