NOTE:
Keep paragraphs as short as possible and make the letter punchy.
Have a right mixture of technical terms without using short forms for any of them. (People reading these are HR not technical everytime)
You can have more paragraphs if your sentence formation is good, but do not have less than 4 paragraphs.
Try and limit your Cover Letter to 1 side of an A4 page.
Do not change formatting or bold any of the text. It is a one page report on yourself. Keep it simple and to the point.