Hi @sagrawal ,
From AEM core components perspective, we follow BEM like convention for css and use style system based presentation layer modelling. Please refer to  and  for best practices.
Thanks for above information.
1. Is there any other approaches also that we follow for custom stylings.
2. I am developing a list components and want to give provision to author on couple options to show list as
a) Grid option b) Carousel c) Horizontal
So do we have some OOB AEM options (classes/functions) to achieve this.