Helping Your Users Embrace Lightning
Let's be honest, change is scary even when the change, overall, is for the better. As Salesforce inches closer and closer to the Lightning UI being the one-and-only, you have to be ready to help your users embrace Lightning which involves much more than simply allowing them to access it.
First, and foremost, Lightning needs to be optimized for your processes and end users before it is officially rolled out. If you opt to simply turn on Lightning, can ensure you that the experience will be less-than-ideal for the end users which can permanently taint their opinion of the UI. Salesforce has a built-in tool to help with the roll-out process called the Lightning Experience Transition Assistant and encourage you to check it out but will also detail what I have done while introducing Lightning to a company.
In order to optimize Lightning in a way that will be appreciated by end users, I begin the process by recruiting one, or a few, individuals from different departments/roles to provide feedback that can be incorporated into changes reflected in things like Lightning pages, Lightning Apps, and more. By understanding what the end users need from Salesforce, that knowledge can be applied when building functionality within Lightning to help support, and possibly improve, their current processes and usage.
As Lightning is optimized, continue getting feedback from your test user(s) to help guide the creation of training material. As far as training goes for Lightning, the earlier the better. Again, change is scary so if you can slowly introduce Lightning, and its features, to your users the transition will be smoother and less abrupt for them. You can begin training before turning on the Lightning experience and cover topics such as a general overview, navigation and search, and reports and dashboards. I prefer to hold these trainings live (in person and via webinar) so that end users have the chance to voice their concerns and ask questions. I also record them so they can be referenced later as needed. As you get closer to "releasing" Lighting, trainings should get more in-depth and you may want to create written documentation for reference as well.
Let's say you are ready to let your end users experience Lightning, you have optimized it for your end users and their processes and have held several trainings, and while you may be excited, try and take it slow. Once Lightning in enabled, have found that an encouragement of using it 1-2 hours/day to begin with allows end users to grow accustomed to the interface and protects them from feeling like a cord has been cut if you took Classic away, fully, immediately. Generally, even the most vocal Classic supporters will build a level of comfort with Lightning over time and might even surprise you by spending more and more time in the UI.
So, Lightning is rolled out, your end users are utilizing it more and more, you're done - right? Not quite. With every Salesforce Release comes updates and new features with the vast majority focused on Lightning so you want to ensure that you stay on top of applicable changes and communicate those out to your end users. By promoting what can be done in Lightning, you are only helping your users appreciate it further.
Outside of releases, you can also help shift people over to Lightning by building new functionality that only works in Lightning. A bit tricky, maybe, but it helps reinforce that Lightning is the future and what should be relied upon while working in Salesforce. I did this recently by creating a Flow for Sales Reps to quickly, and easily, create a Case from an Opportunity (and then populate a field on the Opportunity referencing the Case) which can only be accessed in Lightning as I did not create a Classic button for the Flow and only have it available as a component on the Lightning page.
Now, before I wrap up, I want to say that Lightning is not perfect and some complaints especially related to functionality, and speed, lost from Classic are warranted but at this stage I do believe that Lightning is something to embrace and will only continue to improve.
Have you rolled out Lightning at your company? Let me know your tips and tricks!