Any advice for leading a small ITSM team?

Start with the people and the work they already do. Ask the team to walk you through a typical incident, change and request, including the bits that happen outside the documented process. Find out where they spend time chasing other teams or making judgment calls without clear ownership.

Then review the existing procedures together and agree on a few basics. An existing team may have useful practices worth keeping even if the documentation is thin.

Take a hard look at the CMDB before relying on it for decisions. Pick a small sample of configuration items and compare what's recorded with what's actually deployed. Check ownership and relationships as well as whether the records exist.

Bad data can undermine incident routing and change impact analysis. You don't need to fix the entire CMDB at once, but you do need to know which parts can be trusted and who will maintain them.

ITSM can't be a little island that owns all the processes while everyone else works around them. Talk with the teams that handle incidents and changes about where the current handoffs break down, then agree on responsibilities together.

I'd be especially wary of adding approvals or mandatory fields just because the tool allows them. Each step should help someone do the work or make a better decision.

Get a baseline before setting improvement targets. Even a simple view of incoming work, backlog and how long tickets stay open can give you a starting point. Check how consistently those fields are used first, though, or the numbers may tell a misleading story.