What tips would you suggest I add to my letter explaining why I had three 90 late payments in past

Hi ryanerika!

Welcome to forums!

I guess you are planning to write a hardship letter. You can check out the given page to know about what to write in that letter:
http://www.mortgagefit.com/problems/hardship-letter.html

You will also get a link to a sample hardship letter in that page.

Feel free to ask if you have further queries.

Sussane

since we have no idea of the reasons for your being 90 days late 3 times, it's a bit difficult to describe how you ought to write the letter. you can use that sample hardship letter, but if you want to be specific about your own struggles, you'll have to rely on your memory to help with that.