Found some useful points to keep in mind when asking for LOR ..................

How long they have known you
how their experience was in working with you
on what activities they have worked with you
how their assessment about your personality/intellectual capability
how they rate your possible success in accomplishing residency program
what they think you can offer to a residency program
History Taking/ physical examination/work ethics/medical Knowledge/team Leader/Clinical Skills
Academic Performance- Presentation/Publication/ Teaching/Audit

Initiative, dedication, integrity, reliability, etc.
Willingness to follow school policy
Ability to work independently
Previous positions held
Summary of job responsibilities
Strengths, skills, and talents
Ability to work with a team

Hope it helps.