For internal hires - we focus on their emotional on-boarding for the first couple of months. Ensuring that they become inculcated in our culture - which includes things like restricting the amount off hours an individual can work and not even attaching KPI' s for the first month or even two (depending on the division and the need). We tend to focus a lot on how they are feeling emotionally while adjusting to the new environment (including a revamped buddy system - although I dont like that term). This approach has worked well for us and we have seen our attrition rates reduce significantly across all of our brands because people are in the right head space before we attach the inevitable pressure of KPI's.
After seventeen years of recruiting, I have seen allot of things good and bad to enhance the candidate experience. One of my favorite things weather as a full time or contractor is I pick up the phone about two or three days later and followup I ask them if everything is all right, are they getting what they need etc. I found this increases my referrals, builds a positive image of HR/Recruiting as well as good relationships. I do this either emails, phone, or in person if possible.