Altitude is important.

Check chests for new resources. Boss markers typically found in stone towers.

If you find stone golems around there is a high probability of silver being in the area.. for sure at that altitude and above.

Don't be afraid to dig around. They put extra silver veins in since the wishbone will not find all of them. Some may be too close to the surface and considered not buried or hidden so it won't ping the wishbone.