Up down and across...
You have a new manager, a new junior colleague a new peer. What do you do?
If you hear about them ahead of time (mostly you will but we know how that's not always the case) how about connecting with them on LinkedIn? Welcome them to their new role, and ask them what they are looking forward to most about the role.
Their first day? Greet them when they arrive, or call them to say "Hi" and if possible have a coffee, tea or meal with them. (do you know many employees decide they will stay long term in their new role within the first two hours of day one!).
Be on time for your first meeting with them.
But going beyond the basics, I would offer that you borrow from coaching and "contract" with them. Take some time to ask how how challenging they are comfortable with you being, how they like to receive information, how detailed oriented they are. Find out what their "style" is for receiving feedback, for absorbing information, and how they deal with pressure. Being upfront about these nuances of interpersonal actions helps speed integration and welcomes them more intentionally.
How do you build relationships with new team members?