I want to improve my score

I want to begin the process of putting an end to my credit nightmare. I have a few questions, which are:

1. I have a collection account. My Experien report shows that it was sent to a collection agency named xxx. My Equifax report shows that it was sent to yyy. Am I correct in thinking that I first need to send a verification letter to both the collection agencies?

2. I have a charged off account. My Experian report shows that it began showing a negative status on 10/2003, when it was 30 days late. It shows several 30, 60, 90, 120, 150 and 180 days lates. About a year ago I thought I would try and pay this account and called the collection agency. I ask them to reduce the total amount owed and they laughed at me. So, I decided to forget about it and do nothing. No contact with them since then. Is there any way I can make this look a little more positive, or delete it all together from my report? Also, Experian usually shows the date at which the account should be deleted from your report, however in this case no date is shown.

3. I also have another charged off account. I paid this account after it was charged off. Again, is there any way to delete this from my report?

My FICO score is very low. 599 with Experian, 572 with TransUnion and 630 with Equifax. I would like to try and raise it and establish a better credit history. Any help in doing so would be greatly appreciated. I live in Illinois.