With the weather out here in California constantly changing from hot, to windy, to cold, and back again, I noticed that North's  ears tend to get dirtier faster (especially with us hitting the beach more often in the Summer months). I like to clean his ears about once a week or so with Fuzzyard Organic Ear Cleanser  ($22) that contains Aloe Vera to soothe, and a mixture of Almond and Macadamia nut oils to soften stubborn wax.
But, if you aren't keen on the liquid solutions, I learned that Samson  uses Earthbath Ear Wipes  ($9) that come in a jar of 25. Since they are all natural, they don't sting or burn, and LilPeaPod tells me they work great! If your pet is a swimmer, it's especially important to keep an eye out for ear infections, and cleaning regularly will help stave off any problems. What do you use to keep your pet's ears clean?