  Quantum metrology can achieve far better precision than classical metrology,
and is one of the most important applications of quantum technologies in the
real world. To attain the highest precision promised by quantum metrology, all
steps of the schemes need to be optimized, which include the state preparation,
parametrization, and measurement. Here the recent progresses on the
optimization of these steps, which are essential for the identification and
achievement of the ultimate precision limit in quantum metrology, are reviewed.
It is hoped this provides a useful reference for the researchers in quantum
metrology and related fields.
