A simple structure works well: why this firm or office, why consulting and why you, then a short close. You do not need five separate sections or a creative opening to make the letter effective.
The strongest letters connect the candidate’s evidence to the firm rather than making broad claims. Instead of saying you are analytical, show one short example that demonstrates it and explain why that experience is relevant to consulting.
Keep the letter concise. Recruiters should be able to understand the main message quickly, and the resume should still carry most of the detailed evidence.
The goal is not to sound unique in every sentence. It is to sound specific, credible, and easy to follow. A useful reference is how to structure a consulting cover letter.