The Hero of the Day achievement is relatively straightforward.
I have checked my completed quests in the menu screen and have the following completed.
Find a Village: This is what you start off working towards at the beginning of the game.
Find the Mayor: Markovna Mayor Hleb is missing. He is located in the Werewolf Den in the far North West of the Croakwood map. Be prepared. As there are a lot of enemies.
Speak with Romany Leader: In the South East of Croakwood, there is a Romany Camp. Talk with the leader for a quest to hunt the dangerous Snowpelt.
Escort the Merchant: This is also a separate achievement, Escort Master. (Please see my guide on how to achieve that in better detail) Simply escort the merchant to the Romany Camp.Just north of the entrance to Croakwood to the South East camp.
Journey to the Ink: Speak with the Alchemist in Markovna. Then enter the well. Make it to the end of a short an easy map, to retrieve the Alchemist satchel.
Rusalka Ambush: After saving the Mayor. He will give you this quest in the village. It is at night, so no villagers will impede you. Be prepared. The enemies can quickly swarm you and deal massive damage quickly. Simply kill all enemies on the village map.
Living Ghost: In Croakwood, to the West and slightly North of the entrance to the map. You will meet a wandering ghost. Interact to get him to follow you. In your mini map, a small circle will pulse away. Take him to the area, to help him realise his predicament. Then defeat him. Quite easy.
These are all the missions that I've completed to get the achievement. I hope this works for everyone else. If there is anything that needs updating in my guide. Please comment and I will rectify it with credit to you.