Let's get this out of the way -- it should be obvious by now.
So start with mobile!
So start everything you do with mobile. Mobile first is more than just a starting point.
And keep it simple.
Don't complicate things unnecessarily. Fortunately, thinking 'mobile first' forces you to keep things simple.
Am I boring you yet? You've likely heard this before or it seems obvious, but let's drill down to make sure we fully understand why we should be mobile first.
What makes it mobile?
What about the mobile experience is so different that we should think about it first?
What makes it mobile?
Hand-held device
Smaller screen
Probably used in shorter sessions
Touch interface
Possibly slower connection
Possibly used in a location context
[REVEAL] Yes, these things differentiate a mobile experience from a desktop experience, but they also present opportunities for making a better user experience on all devices.
Making your design, your funcitonality work in the hectic, cluttered mobile world...
...makes your user experience better in a desktop environment.
Mobile apps are your competition.
Good mobile apps developers know how to cram lots of content into small spaces and make it accessible. We need to do that too.
Speed is your competition.
Your users have come to expect everything is fast. Bad design can slow them down, regardless of whether they are viewing on a mobile or desktop screen.
These are all things to think about before you begin a design. That's thinkiing outside the grid.
Now let's think inside the grid.
Grids are nothing new.
The idea of using a grid to layout something has been around for centuries. Newspapers adopted them to organize content and make it easy for the reader to flow from one story to the next.
To be responsive,you have to be flexible.
It's easy to get locked into a grid pattern, but that will cause you and your user grief if you do. Keep your grid flexible.
Grid Frameworks
Adopting a grid framework can take out a lot of the work while gaining all of the benefits of a grid.
Advantages
A quick start to designing.
Unifomity and structure in the design.
Repeatability and maintainability.
The advantages have made frameworks widely adopted.