What is the preferred way to set environment variables at emacs initialization?

Question

For instance, suppose I want to modify my PATH variable in my .emacs file. What is the best way to do this? Should I call setenv? Is there a variable I can customize? Should I call a shell script

Answer 1

You got it right:

(setenv "PATH" "some;/path/that/you/want;/really/this/is/the/path")

The bigger question is, why do you want the path to be different just inside Emacs? Is it to tell Emacs to find the appropriate applications for ispell or shell? There are more straight forward ways to solve those problems.