What is better to indicate in a letter of recommendation for a web master in an SEO company?

Question

PHP

I'm leaving the SEO company, I was offered to write a letter of recommendation myself. I'm scratching my head about what is better to enter there, and what is not worth it. Compose only from the position, duties and skills, or add personal qualities?
He worked as an optimizer, but besides that, he finalized and created sites from scratch, from design and layout to programming. If you enter everything that is possible on an A4 sheet, then of course you get porridge.
Advise someone who understands this, what would be useful to indicate, and what is better not to indicate at all?

Answer 1

Try to put yourself in the shoes of the employer reading this letter of recommendation. What will interest him in the first place?
It seems to me that specifics are needed: what projects and cases, what is the contribution.

Answer 2

If the main job of SEO is - Then focus on it. Indicate, for example, the three most successful projects, what were the problems and what was done, what were the results. What is your personal contribution?
Regarding site improvements, make a small paragraph for 2-3 lines, indicate what you did, what you can do and what technologies. The future employer will be interested in what you can do yourself without contacting a programmer.
Personal qualities can be indicated at the end in one sentence, where the employer recommends or does not recommend you as an employee.