1. Don't contradict the lore that is already established: Bethesda does this a
LOOOOOOOOOOOOOOOOT. Case in point: A cure for being a super mutant, an ancient alien city underneath the Mojave, 300 year old vampires, a ghoul kid living in a fridge with no food or water for 200+ years. I could go on.
When there is already established lore, respect it and don't try to change it because you think your changes are cooler, more fun, less boring and better than the original. (Right Pete Hines?
)
2. Make settlements be believable: Bethesda loves to make their settlements into theme parks as they go with the "rule of cool". As such, they make no sense. Like having a major settlement be in the middle of a atom bomb, a city that is a naval carrier, a city in a ball park, ect. It makes people ask questions like; "How are they able to farm for food?" "Why would they live in an area so dangerous?" "How are the people in the town able to support themselves?"
While settlements that should have a large population and business going on like Canterbury Commons, which we are told is the trade hub of the Capital Wasteland, is a pitiful small town when it should be something close to The Hub.
3. Post-apocalyptic tone: This, at least to me, can be described as being brutal, dark and with mostly grey morality. The post-apocalyptic world is rarely a black and white world. Desperate times make desperate men. Forcing them do things that they will normally never do in order to survive or support loved ones.
4. Don't be afraid to put in mature themes: Bethesda is either really scared to put in mature themes in their games or would rather pander to the Fortnite kiddie crowd. (I will go with both but is mostly the latter.)
A post-apocalyptic world is a brutal world. We see how humanity would be without laws and government enforcing a set of rules and consequences. Things like slavery (even child slavery), drug addiction, prostitution, murder and even rape should be, while sadly, all too common in a lawless wasteland.
5. No fucking aliens!: Just stop with this. Please. Aliens in the original Fallout's were just goofy, tongue in cheek jokes. They were never meant to be canon. Let alone be the cause of the Great War. (Jesus Christ Bethesda. What were you thinking with that?)
and finally, the most important rule, least for me is...
6.
DON'T MAKE FALLOUT BE FOR CHILDREN: Jesus Christ Bethesda... This is, or at least was once, a Mature rated series that dealt with things like: drug addiction, prostitution, sexism, homelessness, bigotry, slavery, sexual abuse, murder, genocide, rape, violence, human experimentation, political intrigue, xenophobia, class disparity, war, ect...
You should not be making a series like this be for little kids. Hollywood and the entertainment industry need to stop with that. There is something like Star Wars and Marvel, which is for all ages, and then there is stuff that should only be for a mature audience. Fallout should be in the latter.