Subject: Always put something in the subject box to indicate what the email will be about. Have a think about what you are going to write, and try to think what the overriding topic of discussion is.
Addressing the reader: This depends largely on whether or not you know the recipient. If you know them, you would launch into the conversation as if they were in the room with you. If you do not know the recipient, a simple ‘Hello’, is perfectly acceptable.
Paragraph 1: Do not indent your paragraphs, merely write as you would in a normal letter, following the usual formalities. Try to be concise and remain polite and friendly.
Paragraph 2: Use this as a conclusion. Go over any important points that you have mentioned previously, and indicate that you are looking to hearing back from them.