If you want to do an efficient relaxation from a configuration that is not close to the minimum, set the following values in the INCAR file (for briefness the recommended setup is lacking, see Sec. 6.2.3):
NELMIN = 5 # do a minimum of four electronic steps EDIFF = 1E-2 # low accuracy EDIFFG = -0.3 # accuracy of ions not too high NSW = 10 # 10 ionic steps in ions IBRION = 2 # use CG algorithmThis way only low accuracy will be required in the first few steps, but since a minimum of 5 electronic steps is done the accuracy of the calculated electronic groundstate will gradually improve. If you are a slightly advanced user you can also use the damped MD algorithm, which is usually more efficient than the CG one:
IBRION = 1 ; SMASS = 0.4 # damped MD POTIM = 0.4 # time step needs to chosen with careIn this case, a too large POTIM will result in divergence.