When I am writing a module to Magento 2 what should i do (front-end).
I recommend taking the Magento U online courses as a start which are free until January 31th. You can find them at https://u.magento.com/magento-2.
Of course, you can also take an on-site training or get into Magento 2 development by reading books and blog posts. Sorry, your question is much too generic for a more concrete answer.
Sorry I did not reply sooner. I try to ask again more specifically.
First of my questions was about issues which fall under Magento core problems. Meaning when it is justified to post to github Magento2 repository problem as Magento2 issue!
Second question was about tutorial which would narrow down the spot where issues would be located (I am posting it hire because it is programming related).
Two user case to explain better what I ask: