My weak point but my passion. Started with php working on webapps for brands like MINI and DIESEL, and now my path is cristal clear towards Ruby. Love to work with people that know more than me. I'm always learning.
Optimization
It must load fast. In the mobile web of today its part of the job. My workflow and strategy checklist includes image optimization, code minification and the use of devtools to bring reasonable loading times at 3g speeds.
Front end
css / html / js skills using frameworks and tools as needed. Been using Foundation for a while, and love where is headed. I also always use any library out there that helps out.