#1- Transition does not have to be all or nothing
For Visualforce Developers, when it comes to transitioning to Lightning development, it does not have to be an all or nothing deal. Very few development shops/companies will go from doing all Visualforce development to doing all Lightning development overnight. That is just not realistic, nor a good idea, in my opinion.
The introduction of Lightning Out offered a lot of options for Visualforce developers wanting to slowly transition to Lightning. If you want to learn what options are available in terms of a transition plan, I suggest checking out this post and blog series by Salesforce Architect, Mike Topalovich. Mike does an excellent job, not only of giving a lot of background, but of detailing 5 specific migration paths that you will want to consider.
#2 – Watch your Casing
If only I had a nickle for every time I ended up discovering that the odd error I was getting in Lightning was actually caused by a casing error of mine. Seriously, I cannot tell you how many times this has tripped me up. More times than I would probably like to admit.
#3- Security Works Differently
As Visualforce developers, you have been spoiled as far as security is concerned. Visualforce apps operate out of the Force.com domain, which is not shared with Salesforce code. But, Lightning apps and components run in a special domain that is shared with Salesforce-authored Lightning code.
This means that the security for Lightning components are subject to a Content Security Policy (CSP). The rules surrounding what is and what is not allowed with these components will just tighten as time goes on. Go here to learn more about all the concerns regarding Lightning Security.
One important thing that you need to know is that any of your AuraEnabled Apex classes must do an explicit check for CRUD and FLS permissions. This was handled automatically for you in Visualforce pages, but in Lightning, unless you are using the new Lightning Data Service, you will need to do this check manually. You can do so using the isAccessible(), isCreateable(), isDeleteable(), and isUpdateable() methods. You can learn more about how this is done here.
#4 – Install and Use the Lightning Inspector
For Chrome users, there is an excellent plug-in called Lightning Inspector that every Lightning developer should check out. One of the most useful features it offers is a component tree tab, which shows you how the Lightning Framework sees your component. You can use this as a tool not only for debugging components, but learning more about what some of the built-in ones are capable of.
#5 – Check out newest components/features added
The Lightning Framework has been out for a while now (over 2 years actually) and in that time there have been many new releases and lots of new features added. Building Lightning components today is not the same as it was when you may have run through a tutorial or article a year or two ago. If it has been a while since you took a look at what features and components are available, it is time to take another look.
In the last release (Winter 17) many new features were added such as the Lightning Data Service, which you can kind of think of as the equivalent of a Standard Controller for a Visualforce page. Currently this feature is still in developer preview, but using it allows you to eliminate the need for Apex code and also those manual security checks that I mentioned earlier.
I strongly believe that component-based development, such as what you do with the Lightning Framework is the future of web and device-based development. If you have not already dipped your toes in Lightning Development, it is not too late. Things are just getting really good for this modern development platform.