'Choke up' on the q-tip, holding it closer to the business end such that your fingers prevent it from being inserted further than intended. That's what I do anyway.

YMMV of course, particularly since earwax consistency is apparently something that varies considerably between different populations.

don't ever move when using them, period, lol

Also don't jump on a couch at the dentist with your new tooth brush in your mouth and land face first requiring an emergency room visit to stitch a hole ripped into the back of your mouth.