From Boston.com: How to raise your credit score - Personal finance - Boston.com
There are trade-offs between taking advantage of 0% offer (FICO damage) and high credit balance as well as between applying new credit cards (FICO damage) and the associated offers.
Even taking low-rate HELOC may have some impact on one's overall FICO score. There is no free lunch as we all find out sooner of later.
Hitting a balance according to one's own financial situation is the key.