如果你要請別人幫忙，并且可能不會有多少報酬，還要占用對方的時間或是花費金錢，這樣的求助成功的可能性不會很大，除非你能說服對方這件事能給他帶來潛在的益處。

商業上求助的時候，通常都要寫一封說服信。下面是求助說服信的寫作原則：

1. Learn all you can about your reader and tailor your request to the reader's interest or concerns.
2. Find rational, emotional, or moral appeals that might attract your reader's attention.
3. State specific benefits which your reader might value.
4. Offer enough information upon which your reader makes his decision.
5. Close by making your request confidently.

下面是一封邀請演講人的信，大家來看看這封信是如何寫的：

Dear Dr. Longh

Your recent article "Major Principles of Financial Management" in the Journal of Financial Economics has drawn many favorable comments from our managers and bankers.

Although many middle level managers have experience in the financial field, some of us lack theoretical background. We, the Financial Manager Club, feel a strong need for more practical guidelines in financial management. Your expert opinion would be a big help to us.

About 150 financial managers will be attending our annual managers' meeting. They would be glad to meet you and share their problems and concerns with you.

Being a speaker at this annual meeting, you will be able to present your perfect specialized experience which is supposed to be reported on China Daily, one of the popular newspapers in our country. In the meantime you will also have an opportunity of meeting some of the executives from major banks and corporations.

Your wife is also invited to be our guest at the banquet, which is to be held at the Golden Dragon Hotel on Friday, May 3. The schedule for the program is:

Cocktail 17: 10 - 17: 30
Presentation 17: 30 - 18: 10
Questions & Answers 18: 10 - 18: 40
Dinner 18: 40 - 20: 00
Entertainment 20: 00 - 21: 00

The program needs to be announced to our club members on April 30. Will you kindly let us know by April 29 whether your busy schedule in Beijing will enable you to accept our invitation?

We are looking forward to your favorable reply.

Sincerely yours

（例文來源：《國際商務寫作教程》，對外經濟貿易大學出版社 英語點津 Annabel 編輯）