Credit score help

I have had a 650ish score for several years now since I started tracking. I have increased my available credit and have reduced my credit usage percentage over the past year. I do have some charge offs, about $3k, that are more than 3 or 4 years old, but they only show on some reports. I have have near perfect payments over the last 3 years, last 4 car payments were slow paid. I can provide credit reports. I just need to get to 690 in about a year so I can get a lower interest on a car loan.