I use a q-tip and am very careful. My little Yoshis ears are so tiny that there isnt much choice. I also use the ear cleaner liquid formula I get at PetsMart but I do not put the liquid directly into the ear as prescribed, I wet the end of the qtip and very gently clean the ears. I have never had to go deep into the ear though, due to I havent let it get to the point of being very dirty way down.
I get the "outer edges" with a q-tip but I'm too scared and Cooper's too wiggly to even attempt to get anywhere near the inside of his ears. For that, I bought some ear cleaning solution that you squirt in the ear, rub around and let them shake it out. He loves that (NOT). Then I take a tissue or cotton ball and clean any mess that comes out. After that, I hold him and tell him how much I love him as I spin him around to do the other ear and he freaks out, screams like a stuck pig and usually gets free of my grasp. I keep a chart to remind me of which ear I got last time so the next time, I can get the other.
I wouldnt reccomend a Q-tip...we have seen many dogs come in with inner ear damage because owners used q-tips...even if you are careful if your chi decides to jump or something you can accidently damage their ears.
Use a cotton ball...if the ears are not bad you can use some warm water, but if you see build-up in the ear or start to notice a smell and your dog seems to be shaking its head and scratching at the ear its time to visit the vet...there they can see if you dog has ear mites or a yeast infection, at the very least they can sell you some ear cleaner.