Here is a detailed guide for the "Big Business" quest in Genshin Impact. Remember, this guide reflects the general gameplay as of this writing. If there have been recent changes or updates to Genshin Impact specifics like rewards or exact quest mechanics might differ.
Image via HoYoverse.
Unlocking the Quest 
1.Prerequisites: This quest might become available after reaching a certain Adventure Rank or after completing specific storyline or event quests related to Liyue or merchant activities. Typically, you'd expect it around AR 20-30.
2.Starting the Quest: Begin by talking to an NPC in Liyue Harbor, often someone involved in trade or business like Mr. Zhu, or it could be triggered by interacting with a notice board or receiving a letter.
Quest Walkthrough
3.Meeting the Quest Giver: Start by speaking with the NPC who has a business proposition or needs help with a commercial issue. This could be at the docks, near the market, or at the Feiyun Commerce Guild.
4.Gather Information or Goods: NPC Interaction: You might need to speak with various merchants or characters around Liyue to gather information or specific goods. This could involve:
5.Bartering or negotiating prices.
6.Finding rare materials or ingrefornts.
7.Delivery or Escort: Delivery Mission: Deliver goods to another part of Liyue or even to another region. Watch out for bandits or monsters along the way.
8.Escort: Escort a merchant or a cargo cart safely to its destination.
9.Resolve Business Disputes: You could be involved in resolving disputes between businesses, which might require:
10.Solving a puzzle or mystery related to lost or sabotaged goods.
11.Mediating between rival merchants or dealing with corrupt officials.
12.Combat or Stealth Section: There might be a part where you need to deal with Treasure Hoarders or other adversaries trying to steal or sabotage the business deal.
13.Negotiation or Auction: If the quest involves a high-stakes business deal, you might participate in a negotiation or an auction, where your decisions could affect the quest's outcome or rewards.
14.Conclusion: Return to the quest giver to wrap up the deal. Depending on your success, you might need to finalize the business transaction or report back on the situation.
Quest Rewards
•Primogems: Standard reward for quest completion, around 40-60 Primogems.
•Adventure Experience: To help increase your Adventure Rank.
•Mora: A sizable amount for your efforts in the business world.
•Character EXP Materials: For character development.
•Special Trade Goods or Recipes: Sometimes, quests like these reward unique items that can be used for crafting or cooking.
Quest Tips 
•Bring a Diverse Team: Have characters with different elements for any combat or elemental puzzles you might encounter.
•Negotiation Skills: While actual negotiation might not affect gameplay, choosing dialogue options that reflect business savvy could lead to additional lore or different dialogue responses.
•Exploration: Use this opportunity to explore Liyue for any additional resources or chests you might find along your route.
•Time Management: Some tasks might be time-sensitive or benefit from doing them during certain times of the in-game day, so plan accordingly.
•Check Your Inventory: Ensure you have space for new quest items or materials you need to collect.
If "Big Business" has been introduced or if there are specifics about this quest that weren't covered here due to updates after my last update, checking the in-game quest log or recent online guides from the Genshin Impact community would provide the most accurate information.
