Hello there, 
I am new to Cataclysm Dark Days Ahead and have been thoroughly enjoying the depth and complexity of the game. Lately; I have been intrigued by the possibilities of interacting with NPCs but feel a bit lost on how to make the most out of these encounters. I would love some guidance on how to approach NPCs effectively; especially early in the game when resources are scarce; and survival feels precarious.
What factors influence whether an NPC will agree to join me? Do traits like Charismatic or high social skills make a noticeable difference? 
How does the bartering system work in CDDA? Are there particular items that NPCs value more than others, or should I focus on offering essentials like food and medicine?
Also, I have gone through this post; https://discourse.cataclysmdda.org/t/the-game-has-a-shitty-game-design-power-bi which definitely helped me out a lot.
Is there a way to build trust with NPCs over time? Can actions like sharing food, avoiding theft, or protecting them improve their morale or loyalty?
Thanks in advance for your help and assistance. 