Google has published their official advice on the Google Webmaster Central blog on how to handle your home page when your web site serves multiple languages and countries.
Zineb Ait Bahajji and Gary Illyes, Google Webmaster Trends Analysts, wrote the post together trying to break out the possibilities into three categories:
(1) Having one home page that shows all users, no matter of language or location that same home page.
(2) Bringing users to a landing page asking them to pick their desired home page.
(3) Automatically redirecting users to the proper home page based off of various location/language detection techniques.
Google supports all these options but gives guidance in this post on how to handle it in all these cases.
The first method is to have the .com users get the English version, the .fr get the French version, the .co.il version to get the Hebrew version and so on. Each domain name will serve different versions of your home page based on someone accessing the URL of choice. If someone lands on the .com, you may want to show an overlay to users who are not expecting the English version, that you have an alternative home page for that user.
The next option is to send users to a country selector page on your homepage or generic URL that lets the user pick which content they want to see. If you implement this method, Google recommends you use the x-default rel-alternate-hreflang annotation for the country selector page. Google said the x-default value helps them recognize pages that are not specific to one language or region.
The final option is to just send the user to the home page you think they want to go to. You can determine this by detecting the location and language settings of the user and then use a server-side 302 redirects or by dynamically serving the right HTML content. In this case you will want to use the x-default rel-alternate-hreflang annotation as well. Google highly recommends that when you do this, you consider that you offer the user a way out, to go to a different version, just in case you get it wrong or the user prefers a different language.
Google always recommends you add to the country and language pages:
You can learn more about this all on the Google Webmaster Central.