Well, the process of worldbuilding shouldn’t be dependent on the medium of the story. Whether you are writing a work of IF, a novel, the background for a board game, a webcomic, a movie script, etc. you should go about worldbuilding in the same way. So all the standard worldbuilding processes apply. One important thing, as @Spire mentioned, is to be internally consistent. For instance, if you decide that magic requires a heavy cost from its practitioners, then be sure all uses of magic fit with that. Otherwise, as @MeltingPenguins pointed out, you will start to erode the willing suspension of disbelief of your readers and pull them out of the world of the story.
The presentation of the worldbuilding you’ve done, on the other hand, will vary depending on medium. For prose that means writing out descriptions in line with the narrator’s point of view. However, the 2nd person point of view favored by IF complicates things because of the reader’s identification with the viewpoint character. Your diction and the available options work toward building the character, but not all readers may envision the character they are playing in the way that you are building that character, thus leading to a disconnect between character and player. For instance, consider how the description of a city in your fantasy world would change if told from the perspective of an architect, a poet, a soldier, a laborer, an urchin, a noble, etc. and use that to be aware of how diction affects our perceptions of a character.
Also keep in mind that you should do more worldbuilding than you reveal to the readers. You should have at least a general sense of the world’s history, geography, cosmology, cultures, flora and fauna, and so on even if some of the things you come up with never get revealed or explored in the course of the work. For instance, if you have a map of the world/region (which for the style of IF on this site would likely only be a worldbuilding tool) be sure to have places that are only mentioned in passing and not visited and others that are neither mentioned nor visited. I’ve read too many fantasy stories with maps where every place named on the map shows up in the story, which to me constrains my imagination and slightly breaks immersion.
With plot you have to keep in mind that you will have to balance your readers’ ability to direct where the story goes and how their character can react with your need to keep things manageable. For example, suppose you have a story in which your protagonist starts off at a caravan rest enclosure at the foot of a mountain pass and during the night helps fend off an attack. Whether or not they go investigate the source of the attack branches the story while whether or not they sign on to protect one of the merchant caravans heading over the pass might not branch the story immediately but would have repercussions later in the story (such as if they abandon the caravan in the middle of the pass to investigate the caves from which the attack came). Of course, if all your options take them across the pass, then your readers are constrained to that path and not able to, say, head north to join the call for soldiers to defend against raiding hordes or head southeast to the kingdom that quietly encourages its sailors to engage in piracy while officially denouncing the practice. Each of those alternate paths would essentially be an entirely different story and if incorporated into an IF story would be major branches that might not come back together.
And so when you plot out your story you need to do what you can to account for different approaches the character could take along intertwined paths and avoid too many widely divergent paths. It’s one thing to have one branch where they travel through the pass and have to fight off a young dragon and another branch where they enter the caves and discover the attackers from earlier are minions of a young dragon with subbranches for whether or not they learn of the curse the queen of the fey has put on the inhabitants of the caves for disturbing the sanctity of one of the gateways to her realm deep in one part of the caverns and subbranches for whether or not they tried the diplomatic, combative, or stealthy approach to dealing with this threat to the caravans in the pass and it’s another thing to have one branch being going through the pass with all its subbranches and one branch being going to become a pirate with all its subbranches. The first is manageable, while the second, like my sentence, will grow quite out of hand.
