The quick answer is, yes. But it will cost you more than most.
If you can afford to wait six months, you have time to boost your score by about 50 points that will get you a better mortgage. If you can wait a year, you could jump it a possible 100 points. Simply do the following:
- if you don't have a credit card, get one, even if it is secured
- if you have one or more, use them sparingly, but use them. Don't put them in a drawer.
- always pay on time
- always pay more than the minimum due, even if it's just $5 (this alone can boost your score 5-20 points per month)
- always keep your balance lower than 50% of the limit (if you have a high balance and can get it down to this, that's a minimum 20 point boost). Below 30% is an even bigger boost.
- every now and then make a significantly larger than normal payment
- pay all bills, especially utilities, on time. They also get reported to the credit agencies.
Having been where you were years ago, I did this myself and it works.