An ideal Letter of Recommendation supplements your application and bolsters the picture you have painted in your essays.
Usually, 2 LORs are required by the adcom. Thus, both your LORs should portray you in a different light, adding volume and depth to your personality.If both the LORs talk about the same things, it is a bad sign & suggests that people have a limited and/or self-projected opinion about you.LORs are also a measure of how people perceive you and how you get along with others.
Coming from a credible 3rd person, the admission committee tends to take the referrer’s views seriously & a positive and a compelling recommendation can go a long way in securing you an admit.
Summarized below, are the major number of things that can go wrong if not handled correctly…

Craft a unique story

Someone will be reading your letter, so find out who that person is, and then Google them, says Becky Blanton, author of The Homeless Entrepreneur. “Structure your letter around the reader’s role, power, and position,” she adds. “You write differently to HR than you do to a CEO, for instance.”

Use the CAR format

CAR stands for Challenge-Action-Results, and getting yourself in this mindset can help you write something authentic about your mentee. This approach eliminates the generic, one-size-fits-all feel and truly personalizes the recommendation by highlighting a specific accomplishment or achievement. So as you’re writing, think: What was the challenge, what actions did she take to address the challenge, and what were the results of her efforts?

Include facts, avoid claims.

Breaking it down as the instance below:
Wrong: Jane Doe did an awesome job as our editorial intern. Everyone loved her. This is why I’m recommending her for the position.
Right: Jane Doe’s positive attitude and willingness to learn made a huge contribution to our editorial team. She took it upon herself to launch a new franchise that promoted one of the team’s new products, which ultimately led to reaching our goals. She was a valued member of the team. The difference above is clearly noticeable and worth acknowledging.

Quote a client

Strength in voices will add even more personalization. It gives an added validation to your letter and makes it unique and genuine at the same time. Moreover, it becomes a direct testimony to the rapport you share with your recommender.

Tell a story

“Employers don’t care about a person’s work ethic unless they understand how the person works hard,” says Danny Rubin, communications expert and author of Wait How Do I Write This Email ? “A short story about success on the job will impress them more than anything else.” So, don’t just say the person is motivated, driven, and hardworking. Show that by describing a time when they maintained a great attitude throughout a tight deadline, or organized the supply closet without being asked.

Essential Tips

So now that you have an inkling about the importance of the LOR, let’s mention some check points that need your attention before you’re ready with your final version:
And to top it all the LOR should be believable, an LOR singing songs of your greatness won’t impress anybody, & would rather come off as phony. The LOR should be a blend of realism, shared experiences, facts and a mild portrayal of your weaknesses. These are the elements which make a perfect Letter of Recommendation.