This is probably the most common question when it comes to improving your FICO rating that is attached to your Equifax, Transunion and Experian reports.
The first thing you want to understand is that every credit situation is different.
IF you have 5 accounts that are currently reporting on all of your three main files that have a current status of delinquent, raising your score will not take the same time as someone that has only one negative item that was settled on years ago but never updated on their report.
The first step is to take a current account of where your rating is with the three main agencies.
One of the fastest ways to get your score up is to see what you can have deleted from your files, and you go about this by sending dispute letters to the bureaus.
Dispute letters are half the battle in fixing your credit and FICO scores.
The other half would consist of rebuilding a new history of timely payments on revolving accounts such as credit cards.
The hard part here would be finding someone to approve you to get your new history going, and the best way to do this is by using a family member that you live with that has the same address or last name and having them add you to one of their credit card accounts that are in good standing.
What will happen is that their past credit history will be duplicated on your report, this helps you to begin a good track record which would help raising your scores again.
It can take anywhere from 30days to 9months to get your profile back on track.