My credit score is a 452. How do I raise it?

I have credit score of 452 and I am determined to raise it. I am a little overwhelmed, but my question to you is where should I begin first. Should I start with the most recent bad creditors and work my way toward the older ones. I have some that should be removed this year. Should I let them go? I already went to all three credit reporting places on line and started disputes with those who had wrong info. OK. Thanks for your help.
---------------------------
i would try hard as hadees to work on anything bad from today back two years dispute anything on your credit report older than that and pray. get new reported and rated credit do what i did to fix my credit report with and how i negotiated a bp oil charge card charge off, if you have anything like thatjust charge your gas for a year to stay out o more trouble. and hope nothing else bad happens to you in he meantime.
----------------------------
I am getting ready to make my calls. I am going to tell them I would like to settle my account and would they please totally remove it from my credit report or to report as paid in full as agreed. If they agree, I will ask for something in writing say they agree to that? Should I ask them to settle for a lesser amount? Or is that pushing my luck? I also have a car loan and two credit cards that I keep current on, so that should take care of my 3 open credit accounts in good standing. Had them for a little over a year.
------------------------------------------
I called my first creditor. (Comcast). I asked if they would send me something in writing and he said that is a LEGAL issue and they don't do that. He said it was illegal for them to remove it. Best he could do would be marked paid in full after I pay it, so I said I would. Is the LEGAL part of his answer true??
------------------------
in truth yes
but they could change it and say it was their mistake, if they were asked, which they never would be asked. So legally they can change. most utilities do not negotiate. pay in full or don't. they reall do not care, because next time you go to get cable and they check your credit you are stuck unless you pay. the best ones to help you are collections and charged off credit cards which you reopen with full payment and a extra downpayment to show trust. in the end if you pay the bill you have one less unpaid bill in the past due column
AND
you have reduced your balance to high credit limit ratio. your credit may take a instant hit but it will quickly recover with new good credit that is at least 12 months on the bureaus books