I am looking for a simple way to make sites I design usable on mobile devices.

I see this:

http://zomigi.com/blog/examples-of-f...media-queries/

and this:

http://cssgrid.net/

and they seem a very simple and effective way to make the mobile experience usable.

There is also this:

https://www.bravenewcode.com/store/plugins/wptouch-pro/

What is the best way to do this?

Thanks.