How to choose combination of Firefox and Selenium Webdriver versions for web automation? -

if choose latest version of firefox or latest version of selenium-webdriver, couldn't automate few tests because of either not supported in latest version of firefox or latest version of selenium-webdriver.

in such situation, combinations of firefox version , selenium webdriver version should choose? (i mean, should go one/two version of latest firefox version and/or one/two version of latest selenium webdriver version or other combination?)

use whatever acceptance criteria states. if have support earlier version of firefox because in contract or requirement, must test version , use whatever version of selenium necessary