What are the most important guidelines for writing a successful scholarship application letter?

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Your Motivation for the research and subject.

Is It will be an added value to do something new 

Be clear about what it is you are setting out to achieve - why do you need the scholarship? What is your goal and how will you benefit others by achieving that/those goals?

Once all this is clear put it on the page and then refine it down, keep it simple and demonstrate how you can make a difference with the tools you are seeking. 

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1. Academic qualifications

2. Language proficiency

3. Why do you chose this program

4. Why would you be a good fit in this program

In a single word...RESEARCH.  In order to be more successful in any endeavor, and especially where money is involved, one must have a solid working knowledge of the audience he or she is trying to reach.  The most tried and true method of doing so (doing research about the recipient) has become much easier in the digital age.

By investigating the institution granting a scholarship, one can find such things as its mission statement and core values.  With these in hand and by carefully reading and meeting the parameters of the testing criteria, one can tailor the language of the application to reflect the institution's own language, values, and purpose, which increases the chances that the application will be noticed and be moved forward in the selection process.

While this method is not foolproof and by no means guarantees success, it does bring the applicant a better chance of being noticed, and sometimes all a person needs is a chance to meet face to face to make the best impression.

Motivation Letter One of the credentials and papers for applying for a scholarship, one of the key prerequisites for winning this opportunity,

You must complete all the required answers in the form, in order to ensure that the arbitrators and the Selection Committee consider what you have written,

Make your answers clear and specific to all the questions contained in the message, and do not ignore the answer to a question well about others

Do not forget to talk about your activities and skills. At the same time, do not over-express yourself so as not to look overly arrogant or self-effacing. Focus on your volunteer activities and your social and human efforts, because they give you a positive impression.

As for the answer to the question "Why do you deserve this grant?", You should pay attention to highlighting the extent to which you have grasped this opportunity and interest in acquiring new experiences in this field, because it will develop your scientific and practical potential, and because you will add your scientific and practical contributions to studies and research related to it.

You have to answer the questions of the university, and the reason why you choose them enthusiastically shows the advantages of this university for others, especially in your field, and the future that awaits you if you join them,

You should also pay attention to framing your thoughts in a way that is not likely to have two answers, so as not to mix with the arbitrators, and be careful not to contain your answers to any errors, whether language or in style

With greetings (Ehab Salim)

YOu must be precise, brief, to the point, and enumaretaing all your assets so that to persuade them yoi're the one to get this scholarship

to be precise ... direct to the goal....To be skillful ...to have a good experience in the field of education