Keep it short
Three to four paragraphs are enough. A letter that fills an entire page of body text is rarely read to the end.
Open with a reason, not an introduction
Skip "My name is X and I am applying for the position" – that's already in your application. Instead, start with why the role interests you and what you'll bring to it.
Connect it to the job advert
Pick out two or three requirements from the advert and show concretely how you meet them.
- Requirement in the advert
- What you've done that matches it
- What result it produced
Finish with the next step
Add a line saying you're happy to tell them more at interview and when you're available to start. It makes it easy to move forward.