  A self-consistent renormalization group flow equation for the scalar lambda
phi^4 theory is analyzed and compared with the local potential approximation.
The two prescriptions coincide in the sharp cutoff limit but differ with a
smooth cutoff. The dependence of the critical exponent nu on the smoothness
parameter and the field of expansion is explored. An optimization scheme based
on the minimum sensitivity principle is employed to ensure the most rapid
convergence of nu with the level of polynomial truncation.
