Hi

Writing a good LOR depends on the programme you are applying for. As major such as MBA, PhD or MS require different style of LOR.

Here are few write-ups that I am sure will guide you through:

https://studyabroad.careers360.com/articles/lor-tips-for-ms-studies

https://studyabroad.careers360.com/articles/lor-tips-for-mba

https://studyabroad.careers360.com/articles/letter-of-recommendation-for-phd-students

While writing a LOR you can keep following points into consideration.

1) The language of the recommendation letter should be formal.

2) It is always better to write a letter of recommendation(LoR) on a letterhead.

3) It should give an overall picture of your personal characteristics, performance, experience, strength, capabilities and experience.

4) You must try to avoid vague statements