I want to estimate the four parameters of Exponentiated Modified Weibull Extension (EMWE) distribution introduced by Sarhan and Apaloo (2013) with the Maximum Likelihood Estimation. Because the first derivative of the log-likelihood function of the four parameters give implicit solutions then I tried to continue with the Newton-Raphson iteration method. It's just that I am not familiar in determining the good initial value for this method. Does anyone know how to determine the good initial value for the Newton-Raphson iteration method? Are there any special requirements in determining this value?