NopHead is a lead designer of the RepRap 3D printer, and designed the Skyhook that we’re using all the time while printing at Hive. He’s worked out some good temperatures for extruding different materials in this RepRap guide for Newbies, which i’m reprinting here for posterity:

HDPE.raft_temp = 200
HDPE.first_layer_temp = 240
HDPE.layer_temp = 220

PCL.raft_temp = 0 // no raft
PCL.first_layer_temp = 130
PCL.layer_temp = 120

ABS.raft_temp = 200
ABS.first_layer_temp = 215
ABS.layer_temp = 230

PLA.raft_temp = 0
PLA.first_layer_temp = 180
PLA.layer_temp = 160