In case anyone is still looking at how to change the theme twenty fourteen, I have used the plugin fourteen colours and also installed STyles and then STyles: Twenty Fourteen. you will then have a host of options from changing the heading colour and font!! to being able to change the menu styles/colours etc. No playing with the css so bonus for me.
Word of Warning: if you have Mail Chimp lite installed you will have to unistall it otherwise Styles: Twenty Fourteen won’t work.
P.S. I found these plugin suggestions here: http://premium.wpmudev.org/blog/7-plugins-and-child-themes-to-enhance-twentyfourteen/
You might find this link helpful Wendy Thompson http://premium.wpmudev.org/blog/7-plugins-and-child-themes-to-enhance-twentyfourteen/
it suggests installing Styles and then Styles: Twenty Fourteen and you will have a whole lots of other options. Word of Warning: you will have to uninstall Mail Chimp Lite if you have it installed. Otherwise STyles Twenty Fourteen won’t work.