One quick way to have an increase in your credit scores, is by reducing your credit card balances to below 30% of the credit line - that is if you are financially capable. If not, then at least below 50%. Reducing your balances will have a short-term increase in your scoring.
Do you know what your current credit scores are? Much like what Mike said below, call a local mortgage broker/ banker who will help lead you in the right directions.