To fit more text on the page:
* Make your margins smaller so the text area is larger
* Use a smaller font
* Turn on auto-hyphenation
* Look for lines with just one or two words and try to reword those
sentences to avoid wrapping to the next line
* Edit your letter and look for any unnecessary words.
The biggest space-wasters on your page are the lines with just one or two
words. Rewording those sentences or making your margins just a little
smaller will cut out those wasted line-wraps.
Think of it as a puzzle that you solve by simplifying your language
throughout your page. You "win" when it all fits.