There are no rules for indenting in a personal letter. If you want it to look neat and want the reader to be able to discern where one subject stops and another begins, then an indent would be a good idea.
When writing a business letter, you usualy don't indent.
A space when beginning to write an essay.
No, but you do indent in a friendly letter.
When you are starting a new paragraph. The first word of that paragraph MUST be indented.
Yes, it is customary to indent the first paragraph of a letter.
No
At the beginning of each paragraph (except for the first paragraph if you start with a really big letter like they do in some books.)
Please indent your paragraphs. The bay indents the coastline.
The full block format does not indent.
Yes you do. You don't in a business letter.
When writing a formal letter, the action the author of the letter hopes to achieve should be found in the:
The return address on a letter identifies the address of the person writing the letter. It is typically placed at the top left corner of the envelope or letter.