  Dilute impurities and growth conditions can drastically affect the transport
properties of TiSe$_2$, especially below the charge density wave transition. In
this paper, we discuss the effects of cooling rate, annealing time and
annealing temperature on the transport properties of TiSe$_2$: slow cooling of
polycrystalline TiSe$_2$ post-synthesis drastically increases the low
temperature resistivity, which is in contrast to the metallic behavior of
single-crystalline TiSe$_2$ due to charge doping from the residual iodine
transport agent. A logarithmic increase of resistivity upon cooling and
negative magnetoresistance with a sharp cusp around zero field are observed for
the first time for the polycrystalline TiSe$_2$ samples, pointing to
weak-localization effects due to low dimensionality. Annealing at low
temperatures has a similar, but less drastic effect. Furthermore, rapid
quenching of the polycrystalline samples from high temperatures freezes in
disorder, leading to a decrease in the low temperature resistivity.
