I used to work as a paid GM, and built many worlds, and have later been working on many other stories (both by myself and with others). And in my experience, the best way to proceed (again, by my experience, this is my method) starts with one big question...
Have you already started building a storyline?
If the answer is "yes", the best way to proceed is a large series of "why's, and what's" digging further and further back.
Okay, you have a princess... why? Okay, you have this kingdom... why? It was founded by a warlord...
why? He got people to follow him, why? The problems they were trying
to escape that got them to follow him... why? The land was in
turmoil... why? Massive famine... what caused this? Massive crop
failures every hundred years? Why? The goddess of spring leaves during
that year regularly? Why?....
Then you follow up all the why's with "also results in..."
"The Goddess leaves... which means the famine is during a year-long winter."
"The land was in turmoil in the snow... means the warriors fought well
in the snow who survived." "Those who followed were battle-hardened,
hungry, and weary, and fighting for survival." "These attitudes
founded the kingdom. There's a tradition of utilitarianism, doing
what's required to survive. Maybe your princess is drawn to the finer things in life, things of elegance, and is tired of the coldness in her land. Or maybe she's a warrior princess with battle scars. Or maybe she's weak, and an embarassement to her linage. Maybe she's an acolyte of the goddess and fears the next winter. How she fits into her society drastically shifts when you know the whys.
If the answer is "no", then the best way to proceed is from the beginning. Like, THE beginning. As in, "before there were people, before your world existed, what was the foundation of the universe?"
Was it a big bang or was it "created by gods" and if gods, where did those gods come from, how powerful are they, and what are the limits of their power, is the universe real or a simulation, is it the dream of a butterfly... etc. etc. Answer the deep philosophical question about your universe first.
Now the world... is the world created or is it the result of the smashing together of massive hunks of rock? What kind of sun(s) does it orbit? How far is it from it/them that affects temperature? It's tilt that determines seasons? Stronger or weaker gravity (and side effects?) Is it filled with obviously planned mountain ranges and regularly placed ore deposits or would it make more sense to design the terrain in a random map generator? How long as it been since your initial map was the case? Have the continents shifted, have geological events or wars of gods moved things (if the latter, why, what was the strategic purpose?) Shuffle your continents, see where your resources end up. Where did the dominant species on the planet (probably humans for simplicity and familiarity) start from? How did they spread? How would animals evolve for each of the regions? What got domesticated first? Who were the oldest, why did groups leave/split/etc? When did wars happen, why did they fight? How fast did technology advance? Which types of technology were most important? What's ahead of our world tech-wise? What's behind? What are the present day borders?
Also, addendum to that (you'll need to work on it where it fits in) Has humanity contacted anything other than humanity? Before figuring out how they meet, figure out where they come from and how they fit into the greater world. Okay, now that part done, when, with the two storylines, did they meet with their respective cultures? Work with both cultures seperately before they meet. How did the meeting go? How did resulting political events shape the political boundaries? Etc. etc.
2Both are equally valid and depends on why you are building your world – TrEs-2b – 2016-06-01T02:29:56.120
@TrEs-2b If i had to guess... just kinda experimenting – Premier Bromanov – 2016-06-01T03:45:36.057
@PremierBromanov Some users have split their world into many different posts so they can deal with different aspects separately. As for starting, I'd start with a unique reason for that "world" to be special. Then build from there. – Simply Beautiful Art – 2016-06-01T11:55:01.923
Im torn between Too broad and +1. On one hand this definitely is a candidate for being too broad, there are just so many possibilities that could be answers, like every one mentioned in the question, but on the other it has a certain hint of wanting something very specific. There certainly is no Best answer, It depends on what your end goal is with your starting idea, with many paths to choose, but at the same time, even then there are things that are common amongst all the paths to take between those 2 points which could formulate a solid, specific answer. – Ryan – 2016-06-01T15:37:35.923
That being said, I know there was a similar question on worldbuilding before which i believe was closed, asking about the process itself. I can'd find it now but it did have a link to a very useful resource, a list of questions i believe that are important to be answered. – Ryan – 2016-06-01T15:40:22.347
Related (not sure if duplicates but definitely related): https://worldbuilding.stackexchange.com/questions/2/how-can-i-break-down-the-task-of-creating-a-world-into-manageable-chunks
– Tim B – 2016-06-01T16:01:22.4601https://worldbuilding.stackexchange.com/questions/3622/when-building-a-world-what-are-the-advantages-and-disadvantages-of-a-top-down-a – Tim B – 2016-06-01T16:01:42.710
Our Tag info is actually a good starting point: https://worldbuilding.stackexchange.com/tags/worldbuilding-process/info
– clem steredenn – 2016-06-09T05:26:55.757I think this is probably a good question, but it really belongs on the meta. At least, that's what I think – Xandar The Zenon – 2016-06-21T14:00:12.533
@XandarTheZenon Agree; this is a question about worldbuilding, rather than building a world. – Frostfyre – 2016-06-21T16:32:57.100
@Frostfyre how is that different? honest question – Premier Bromanov – 2016-06-21T20:46:01.487
In the latter case, a question deals with the parts of a world, such as government, disease, warfare, or terrain. In the former, a question deals with the concept of worldbuilding itself, rather than applications of it. – Frostfyre – 2016-06-21T22:11:55.317