  We discuss a general strategy which produces an orthonormal set of vectors,
stable under the action of a given set of unitary operators $A_j$,
$j=1,2,...,n$, starting from a fixed normalized vector in $\Hil$ and from a set
of unitary operators. We discuss several examples of this procedure and, in
particular, we show how a set of {\em coherent-like} vectors can be produced
and in which condition over the lattice spacing this can be done.
