What are the considerations of writing effective job letters?

Considerations of Writing Effective Job Letters:

1.     Using appropriate stationery.
2.     Neat typing with proper layout.
3.     Describing qualifications, experience interest, etc.
4.     Avoiding stereotyped opening.
5.     Being specific, definite, courteous and graceful.
6.     Giving names of references.
7.     Mentioning the results of aptitude and intelligence tests previously taken.
8.     Making request for interview.
9.     Explaining reasons for leaving the previous job or for being unemployed, if necessary.
10. Enclosing copies of the certificates and recommendation letters.