A proper and thorough introduction is crucial

A unified on boarding process & purpose articulation will be helpful.

On top, active staff engagement is crucial too

For new hires, they should have one or two introduction sessions in a week with their line manager, so that they understand better of their role & objectives.They should also have a 121 session after they have completed their 90 days probation.

Good point! For mid management level, mentoring is required from the top management level to actively engage them & have them to drive the team towards integration.

Apart from their individual objectives, which we encourage all line managers to do it on a monthly basis, we also have 2 yearly performance review.

Make sure existing active staffs are there to form a culture that welcome new joiners.