Getting PLA to stick to a cold bed
Most of the same reccomendations that apply for adhesion to a hot bed apply for a cold one.  The first ones to come to mind:


really dial in the nozzle height
make the first layer taller than the rest (e.g.: 0.2mm if the rest of your print is 0.1mm)
print the first layer very slowly
print the first layer at higher temperature
use a brim or a raft (on my first printer, that had no heated bed, rafts gave the least deformation)
turn off the part fan for the first layer
adapt your model to reduce twisting forces (relief cuts, print it in parts, choose orientation wisely, etc...)


If your slicer has this feature, you could also try to print with a shroud.