I agree that patience and consistency is the key. Be sure to reward each good behaviour of the pup so they gravitate towards the behaviours that get rewarded like playing with the toy with you rather then playing with their teeth on your skin
Honestly, I didn't find the yelping worked for Delgado. Time outs did (gave both of us a moment to calm down) and scruffing (not harshly) when needed got the point through.
Jasmine - Female Miniature Poodle - born Aug 15, 2010
Loker Delgado Von Stalworth - Male GSD - born Jan 26, 2012
Koda & Zazu - 5 year old male cats
Alex - Male Cocker Spaniel (rescue) - RIP Cuddlebug 2007-2010