I use Zymox ear cleanser at least twice a week, you can check it out here:
Amazon.com: Zymox Ear Cleanser With Bio-Active Enzymes, 4 oz.: Pet Supplies
When I had gone to the vet they told me it was ok to rub a hydrogen peroxide soaked cotton ball around the inside of the ear but it wasn't working and there's been some conflicting research about it anyway.