Calculate absolute values for resistor bridge to use with op amp lm358
Providing your inputs don't go outside the common mode range of the op-amp you are left with two criteria that are important, noise and bias currents. Making the resistors high in value increases the effects of bias and offset current therefore creating an offset voltage error. Having high value resistors also increases thermal noise voltages - this may also be unacceptable.

On the other hand, having values that are too low will impact on current drawn from the power supply. Decide what is an acceptable current to be taken from the power rail, check to see that it does not induce too much self-heating in the thermistor then look at the data sheet for the LM358 and see what possible effects offset and bias currents have in producing error voltages.