I just did this same thing. I started with a 417 credit score. I now have a 706 and just bought a house in August. The whole process took about 18 months. I started with a secured card which I used less than 10% of the available credit monthly (ie. reloaded my starbucks card). I paid the bill before the statement arrived so that there was always on-time payments but never carried over a balance and never paid interest. I disputed every little thing on my credit history, and hey, a few things were removed. It doesn't hurt to try. I paid off a few pesky delinquent bills but I also racked up some student loans. Once my wife and I had enough reported gross income, we paid off our car loan and applied for an FHA 3.5% down loan. We were approved for a brand new 280k house. Credit doesn't have to be scary. There are many resources like nerd wallet that can help you get on track fast.
