The best and first way to raise your credit score is to have someone with experience help you.
The last thing you want to do is tackle this on your own and inadvertently lower your score.
For example: A lot of people mistakenly think paying off old collection accounts is a good place to start but that can actually lower your scores if the account hasn't been reported for a year or more.
I have access to software that will analyze your credit to determine what actions will give you the most results.
Feel free to contact me for more information or help.
Pay down credit balances to 1/3 of their limit. Dispute any derogatory items which you can disprove. Look into RapidRescore.com, they work with credit report providers and can make a huge difference 30 points or more, in a few days to a week.
Some lenders work with borrowers to improve scores. Ask your lender if they are able/willing to help. I've done this for several past clients. Best of luck.