I've been using the Virbac Epi-Otic Advanced for a couple years on my pups. I know you can get it at Petco and my vet also sells it...I use this stuff every other week when we do baths (the Epi-Otic contains a drying agent so I do it after the bath). I basically just squirt some of the solution into each ear and gently massage the base of the ear area for a couple seconds and then let the pups shake out the solution. I then wipe out the outer ear. My pups haven't had any ear issues (no infections or smelly ears) so I guess this routine is working for us!
Here's the one we use...a bottle lasts a long time!
Virbac Epi-Otic Dog & Cat Ear Cleanser at PETCO