If your viva’s not coming up yet, or it’s in the past, find someone to help. If you know someone who has their viva soon, or someone who is finishing their PhD, ask them what they need. Don’t assume that you have all the answers or the right way to do something. Check what they need first. Then see if you can meet those needs. If you can’t, see if you can figure out what else might help.
If you don’t need help, what can you do to help someone?