Moving to Black Void from Other Systems

It can be tough to transition into playing Black Void from other systems for a lot of reasons, from the complexity of the system, to the more narrative nature of mechanics which aren't as cut-and-dry as you might be used to, to the world of Llyhn itself being wholly foreign.

There's a number of ways you can mitigate your issues in Black Void, the first I would recommend is to pick a "thing" for your characters when building them, specialize, min-max your stat distribution a little. The system is narratively driven, but with the point distributions available to you by default, your options are to either be a nobody who's purely okay at everything, or a somebody who's pretty good at some things and awful at others, and that's okay.

I highly encourage you to spread out your specializations throughout the party to achieve variety in what you're all capable of. It'll feel good in the traditional "party role" sense, in that you get to be a useful character mechanically, but it'll also add a real sense of depth to the narrative being told in the campaign when you're someone who's big and strong and tough, but folds to the sight of the horrors of Black Void.

Pick flaws that seem detrimental, they're supposed to be! Black Void wants your character flaws to feel like flaws, and not just stat adjustments for min-maxing, it wants characters with low stat numbers to really feel out of their element when that trait is running the show, and it wants characters with high stats to feel like they have a noticeable advantage over those who don't in their own arena. It'll really become obvious in game, just give it a try, and don't forget the story matters most!

Accepting the Vagueness

The second recommendation is to just accept the vagueness of the system for what it is: an opportunity to get creative beyond what other systems ever really allow. Consider Dungeons and Dragons, a system in which spells predominantly do one thing, one thing only, and have as few variables as they can to ensure consistency. In Black Void, phenomena are largely described, they're outlined in how powerful they should be, but by and large they allow room for shenanigans galore!

Take the Matter Sphere, for example; you can create objects of various sizes, but it never states what kinds of objects you can create, so you can create a "medium" cube of sandstone over someone's head. Or consider the Mind Sphere, use Delusion to make someone believe that they literally have rats crawling under their skin and watch as they tear themselves to bits.

That's all just the Mysticism system, but everything in Black Void has some looseness, some vagueness which blurs the lines between what is absolute and what can be argued for. If it's a fun idea, give it a chance, pass it along to the arbiter and see what happens.

Shifting the Setting

The last recommendation I have is more for the arbiter than players, but consider a shift in mindset as to the setting. What if Black Void was just a proto-world of whatever your normal campaign setting is? Magic might be something simple and common in D&D, but that's on the shoulders of giants — these people are still drawing power directly from the Void.

Dwarves? I think you mean Naqasti-Kin. Orcs? Descended from Je'ehl-Kin. Give it a try, it's really fun to consider what everything in Black Void's esotericism could mean when given an arbitrarily long separation between then and now.