Though a novice at this unlike the rest of you, 'culture building' has always been at the core of any F/SF work I have done. Whether the highly detailed barbarian culture I developed in 2000-03... to my latest work, post-apocalyptic dystopian near-future 2019, I always start a single way.
A. In general what do I want it to be like in the story B. Where does that specific culture begin. Once I have those two items, I then generate a history from point-B to point-A. As I work on the story, when ideas pop into my head as to how I want the current culture to be, I then work out a reverse evolution along that specific point/line of thinking from A to B... and so the culture grows.
What I don't do is, determine I want it to be like X-Y-Z real life cultures, then try to force them to work. Point-B might be very real life, but point-A is my own, always fictional-- BUT... The growth and evolution between those points, however, is logical/predictable/historical (as in examples as to why a culture changes), and I must invent events in that history that dictates that evolution. Those points are remembered, because, they will also affect each line of development (language, traditions, customs, lifestyle, religions, etc.).
By doing it that way, not only do (I feel and as I've received in feedback) those cultures come off as very real and logical, but they also seem to have a depth and most of all, each aspect supports all others.
In a sense, what I am actually doing, whether I'm starting from cave-men to modern man (point-B), is generating a possible/real alternative history. Reason being... I don't want to 'suspend disbelief.' I want them to come off as a real possibility.
If I do that, then the background (revealed or no) is rock solid, and the story becomes nothing more than a minor story. Just like real life.
EDIT, Addressing the original question: The way I present them so folks know what is going on, is I reference that culture building I mention above and give reasons as to 'why' this particular thing is happening in the story. As an example:
In my latest work, in pastoral areas/zones, I've made it rather clear that there are no modern utilities (electricity, gas, water, sewage) though the infrastructure is still there. I've also developed a ecosystem condition where the surrounding rivers are now highly toxic (contact or ingestion). In one particular PA/Z, unlike the rest, for X reasons there is not even sporadic water supplied via the existing infrastructure. Etc. etc. etc...
In any case, when it rains in every pastoral zone two events take place that have defined the cultures. 1. Water collection for drinking is paramount. Water collected (how varies due to each region's situation) is for drinking ONLY, period. Clothing is government supplied, so discarded at each new rain (never gets washed).
Everyone in pastoral areas (which only single adults live in), verbally warns of a storm approaching, and that is passed on. Each layer/stage of a storm is announced (high wind/debris, dust, mud, blessin/rain, lightning). At wind everyone takes cover where they stand, dust they all strip, mud they brace then scrub, rain they rinse and bathe (communally in Sector V-8), lightning take cover and must share available space remaining undressed (and/or flooding in section V-8 they must get above the floodwaters)... all of that is like a massive choreographed display.
Finally, because of the need for drinking water and the importance of storing it, bathing and so on, the first law of the pastoral residents is the 'truce or peace.' Anyone committing a violent action toward another is instantly set upon by the balance of the population with fatal results. Naturally, that gets us to X point and now the people bide their time other ways with the constant and prevalent crime at zero.
SO, by having one rain in the story, a whole lot of culture/society/traditions/laws/climactic conditions, etc. is demonstrated (with little single sentence blurbs as to why). However, it all makes sense, has reason... and from that also supports and generates other cultural aspects (how would life change living shoulder to shoulder?).
That's why (to me) building off of those historical precedents in the story is so critical. Everything works together and though I then simply tell the story, it hopefully all seems reasonable and plausible.
K2