  We present an optimized algorithm for assigning fibers to targets in
next-generation fiber-fed multi-object spectrographs. The method, that we named
draining algorithm, ensures that the maximum number of targets in a given
target field is observed in the first few tiles. Using randomly distributed
targets and mock galaxy catalogs we have estimated that the gain provided by
the draining algorithm as compared to a random assignment can be as much as 2%
for the first tiles. This would imply for a survey like BigBOSS saving for
observation several hundred thousand objects or, alternatively, reducing the
covered area in ~350 sq. deg. An important advantage of this method is that the
fiber collision problem can be solved easily and in an optimal way. We also
discuss additional optimizations of the fiber positioning process. In
particular, we show that allowing for rotation of the focal plane can improve
the efficiency of the process in ~3.5-4.5% even if only small adjustments are
permitted (up to 2 deg). For instruments that allow large rotations of the
focal plane the expected gain increases to ~5-6%. These results, therefore,
strongly support focal plane rotation in future spectrographs, as far as the
efficiency of the fiber positioning process is concerned. Finally, we discuss
on the implications of our optimizations and provide some basic hints for an
optimal survey strategy based on the number of targets per positioner.
