New credit is essential. You must get 3-4 new revolving accounts (credit cards) and 1-2 installment accounts (personal, car or similar loan).
If you are having trouble with getting new cards or loans, get secured financing. Local Banks offer secured loans where you put money in a savings account, say $3,000 and then you get a personal loan for $3,000. The interest rate is about 0.5% to 1%. When the loan funds, you then have your $3,000 back. Each monthly payment you make reduced the balance and unencumbers the savings. At the end of 36 months your will have a great credit score.
Minimum FICO credit score guidelines
VA Loan – 560
FHA Loan – 550
USDA Loan – 560
Conforming – 580