Go see your vet. They will give you something like Vet Solution to begin with. You should use a cotton ball to apply it. Q-tips are nice, but DO NOT stick it down the ear and just move it about because damage can be done.
I just spent about $1,000 on my pet lab in the last year with ear surgery to open (eliminate) the ear canal area where it enters the side of the head. This "bowl" allowed the build up to pool and create a problem. Things are just getting better now and he has had this problem for 4-5 years. It began with a mild infection in his right ear and after about 2 years it was in both ears. I have been to three vets for help. The most recent has been the best. They also treat my Police K9 and I recommend them to everyone.
The build up can be ear mites, yeast (usually has an odor), or bacteria. If you get on it soon you may be lucky to treat it with some antibiotics. I have tried quite a few things and surgery was the last resort. Atleast he is now comfortable (far more so than before).
For simple ear cleaning and maintence stuff check out Dr Foster and Smith (drfosterandsmith.com).
Good Luck,
Mike