By the age of the group
A group in its first year needs structure from you. People do not yet know what a meeting feels like, so you supply the shape. A group in year four needs the opposite. The shape is habit by then, and the moderator's work moves to noticing when comfortable has started passing for deep.
By format
Virtual meetings run shorter and need firmer edges. Silence on Zoom feels longer than it is, so new moderators fill it, and filling it is the mistake. In person you can let a pause sit. Online you say what the pause is for, then let it sit anyway.
By what the group has already agreed
A written constitution does more for a new moderator than any technique. Attendance, confidentiality, what happens when someone stops showing up: settled once, in advance, and no longer yours to adjudicate alone.
By you
Some moderators run a tight room and some run a warm one, and both work. What does not work is running someone else's room. Printed material nobody edited, a format copied because it was in a binder, a style borrowed from the last moderator: groups can tell, immediately.
On wanting the job
Forums usually ask for a volunteer, so people sort themselves into enthusiastic, considered, and reluctant before anyone has seen them moderate.
The sorting predicts very little. The member everyone expected to be the strongest moderator can be the worst. Someone convinced she could never do it can do it excellently for eight years. Self assessment is a weak predictor here, and it gets weaker the more judgment a role requires, which is exactly this role.
So if you are hesitant, that is not a reason to decline. If you are eager, that is not a qualification. The two questions that actually matter are on the next page.