This less than 5-min video provides key information on how to setup an Exchange Hybrid Deployment.
In addition, the articles below contain updates on topics covered by this video, along with their main takeaways, in bold. Subtitles in brazilian portuguese (my native language) are also available, which can be enabled/disabled from the built-in YouTube player.
"Should we have a hybrid specific URL? - We have seen deployments where a decision is made to keep the existing Mail.Contoso.com and Autodiscover.Contoso.com pointing to a bank of Exchange 2010 servers and have a new hybrid URL, such as hybrid.Contoso.com, pointing to a couple of Exchange 2013 servers. This is an example of an environment that did not introduce Exchange 2013 in a recommended way.
"Some might ask: “Can I keep just my hybrid server up to date?” The answer: there is no such thing as a “hybrid server”(meaning that companies shouldn't add Exchange servers exclusively for hybrid, unless the sizing says it differently). What this question is really asking is: “Can I just update the server were I plan to run the Hybrid Configuration Wizard (HCW) from?” The answer to that is “No.”"
"Before you create and configure a hybrid deployment using the Hybrid Configuration wizard, your existing on-premises Exchange organization needs to meet certain requirements. If you don't meet these requirements, you won't be able to complete the steps within the Hybrid Configuration wizard and you won't be able to configure a hybrid deployment between your on-premises Exchange organization and Exchange Online." Exchange Queue & A: Handling hybrid environments
"With older hybrid servers—that is, hybrid servers running Exchange 2010—you need to create an Autodiscover record in DNS for all SMTP domains. Also, the SAN certificate has to include all used autodiscover DNS records in the SAN list. With the Autodiscover domain feature, you have the option of setting one of your SMTP domains as the Autodiscover domain.This is indeed a great new feature of Exchange Server 2013."
"This article tells you what’s new and shows you how to run the wizard. We also explain the various issues that have been addressed with the new Wizard, and touch on some of the telemetry we pull with every run of the wizard."
"This topic gives you an overview of the Exchange hybrid deployment configuration process, hybrid deployment features and options available to you, and the Hybrid Configuration Engine, which executes the core actions necessary for both configuring and updating a hybrid deployment."