If you wanted to teach your pet parakeet to give you a kiss on the cheek, which technique would be most effective?

I believe the answer is Shaping.

Shaping is a reinforcement technique which use a reward that given gradually after the subject is showing a certain desired traits.

On parakeets, this could be done by giving them a food reward everytime they move their head closer to the place where we want it to be (closer to your cheek)