vovanmix

1. Style existing HTML rather than update HTML. Like, with bootstrap modal and buttons - better to use the default html and add style it with sass, because we can later use js components that will generate standard bootstrap elements and it will be hard to customize their HTML

2. Create CSS classes that will describe semantics of elements and not their appearance. It will help with redesign later. For example, we have all buttons in green color, instead of appending ".green" class to them, better to append "primary-button", and later if we want to make all buttons purple, we just have to change CSS instead of HTML

3. Change CSS is always more easy than change HTML. Because HTML later got split between dosens of components, but CSS(sass) is always in one place. Even more, HTML components can become reusable, and all too strict class naming will become a problem.

vovanmix

$ cd ~
$ sudo curl -sS https://getcomposer.org/installer | sudo php
$ sudo mv composer.phar /usr/local/bin/composer
$ sudo ln -s /usr/local/bin/composer /usr/bin/composer

then you can run 
$ sudo composer install