There are many reasons to write a request letter. Requests generally involve special favours, services, products or information. Whilst requests are very common and routine, the general guideline is to be polite and tactful. If you would like people to respond to your request quickly, you should keep your request:
To increase the chance of getting a favourable response on your request from your reader, you should:
Be sure to state the purpose of the letter in the subject line. It would also be helpful to include any relevant account / customer number, invoice or reference in the subject line.
How you start depending on your relationship with the reader. If this is an unsolicited request, you need to make a simple introduction about yourself, such as your position or company or that you are a long time customer of the company. The introduction should be brief and concise to help your reader understand who is making the request. If you already know the reader, you can start with a simple greeting and go straight to the purpose of the letter. If you are an acquaintance of the reader, have just recently met or been introduced to the reader, you may want to remind the reader of the occasion of the meeting.
The tone of the letter is set in the introductory paragraph which should be polite and courteous. You should keep a pleasant, approachable tone in the letter, even if your request relates to a complaint. It is also good to be tactful and gain some rapport with the reader early by expressing some commonality.
After the introduction, it is also good to state clearly the purpose of the letter of request early in the letter. Be polite and clear about your request. As you are asking for a favour, it would be good to ask the reader politely "Would it be possible ..." or "I would be grateful if you would ..." instead of telling the reader to do something for you.
Explain your request in more detail. You should be clear, direct and focus on the point on what you are requesting. Always be extremely polite and tactful, no matter how frustrated you are. Don't use abbreviations or slang. Be honest and accurate when describing an incident (Including the date, time and location). Any facts provided in your letter should be accurate. Do not exaggerate on what happened or the impact on you.
You should be courteous in your tone and reasonable in your request. Put yourself in the position of the reader when you write to ascertain the reasonableness of your request. Give good reasons for your request and phrase them correctly to increase your chance of getting a favourable response from the reader.
Keep it simple and to the point. Don't dwell on the details. State clearly what you need and express your request in a few sentences. That said, you need to include all necessary information in relation to your request, such as exactly what information, item or help you need, and the timeframe you will need them in.
Give good reasons why you are making the request, in particular in cases where you may need to convince the reader to ask his / her help. Provide any supporting evidence ready and briefly explain why this request is important to you (and the reader if relevant), but not to the extent of putting high pressure on the reader.
Provide some incentives for the reader if necessary (be careful to ensure that it does not constitute bribery). If possible, reciprocate by offering to help the reader. Be sure to show your willingness to cooperate with each other. A simple sentence, such as "If you need more information, please tell me," can tell the recipient that you are willing to work with him and do everything you can in relation to the request.
In the concluding paragraph, you should close it politely by thanking the reader for taking the time to consider your request. You can summarise the purpose of your letter in one to two sentences. Please also inform him / her that you would appreciate a response to your request.