Here are some questions that a student asked me about General Writing task 1:
1. Should I write the date at the top of a formal letter?
No, in the IELTS test you should not write the date or your address.
2. Should I use indentation at the start of a new paragraph?
You can either indent or miss a line. Just make sure it's clear that you have begun a new paragraph. Personally, I think missing a line is clearer.
3. Should I end the letter with "Yours..." on the left or on the right?
Always end the letter on the left. Have a look at my letters on this page.
4. Should I sign the letter before writing my name?
No, don't sign your name. You don't even need to put your real name. Personally, I use a first name (e.g. John) for informal letters, and a full name (e.g. John Smith) for formal letters.