Improve my FICO--besides paying up

[Woodenfish]

I have three problems in my credit.

1. A medical bill that has been disputed for over three years, about $200 worth. The provider was not in the network but led me to believe so.

2. A telephone bill that is in collection. The phone was lost but I had not reported the loss soon enough. The collection agency offers to settle for half, which comes to about $250.

3. My credit card. I have mistaken a series of reminders for payment as solicitation for new services. I have been delinqent without knowing. I have set up automatic payment with my bank but did not realize that the account number has changed. My account is clear now and I am in good standing with the same credit card company, but several late payments have been reported.

I want to buy a house. I had not cared much about my credit until buying another house becomes a possibility for me.

Before item 3, my middle FICO was about 690 but likely due to item 2, I did not get a loan approved.

Now lately there is item 3, the late payments.

I have no problem paying up now, but what do I have to do to get my FICO score up enough for a $250K loan for a house?

Any suggestion is appreciated.

Besides paying up, what steps can I do to rise my FICO quickly?

[diggingout1]

My father has offered to add me as an "authorized user" on a couple of his cards. The card will be mailed to him, and he will destroy it. But, as a result, I will obtain the entire history of these cards on my credit report. Because they have a long history, high limit, and low balance, my FICO should raise considerably. I have heard that each Authorized User account can raise the score 40 to 90 points.

Good luck!