I don't think that trying GMing will do you any harm!
My advice, based on my personal experience as a GM and as a player, would be not to focus too much on your "world" or your "plot". I would suggest coming up with an interesting situation, forming a few ideas about antagonists or further situations that might springboard from that, and then seeing what happens when you frame the PCs into it. Assuming that you have active players who are enthusiastic about playing their PCs, I think you'll find that a little bit of situation can go quite a long way.
It sounds like your group is playing D&D, and obviously the default situation in D&D is a dungeon. But other good starting situations can include someone in distress; mysterious events in a graveyard or a temple; or having to defend a village or homestead from attack. What they have in common is that (i) they easily engage some fairly standard PC motivations (like protecting innocent people, preventing descration of a holy place, etc), and (ii) they invite a range of PC responses none of which is too likely to bring things to a dead-end (eg there are different ways to defend a homestead, both in terms of tactical preparation and also decisions about whether to sally forth, etc; and the attackes can also do things to try and lure the PCs out).
In my experience, the most common way for new GMs (and also experienced but not-so-good GMs) to kill the game is to have a preconceived conclusion or resolution in mind, and to try and short circuit play towards that outcome. Try to avoid that.
And a related point - I wouldn't encourage you to use opposition or antagonists that the PCs can't defeat, or that they can defeat only if they work out the particular solution that you as GM have written into the story. What counts as able to be defeated will be table-variable - at some tables that will mean fighting; other tables, which take social action as seriously as other types of conflict, will include outwitting or charming someone as a standard mode of defeat. At the first sort of table, I would discourage using (say) a local baron as an antagonist, because - if the gameworld is a typical one - low level PCs can't defeat a baron in a fight, given the baron's guards etc. At a table that takes social conflict seriously, then a baron can make a fine antagonist because while he is probably safe from attack he is certainly fair game for being tricked or persuaded!
But an antagonist who can be defeated only if the PCs learn the special secret and then collect the special ingredients is, in my view, a recipe for GM-driven railroading to a foregone conclusion and is a good way to kill the game. I wouldn't encourage that. Make your situation, and its resolution, open-ended. And then let your players dig into it.
My advice, based on my personal experience as a GM and as a player, would be not to focus too much on your "world" or your "plot". I would suggest coming up with an interesting situation, forming a few ideas about antagonists or further situations that might springboard from that, and then seeing what happens when you frame the PCs into it. Assuming that you have active players who are enthusiastic about playing their PCs, I think you'll find that a little bit of situation can go quite a long way.
It sounds like your group is playing D&D, and obviously the default situation in D&D is a dungeon. But other good starting situations can include someone in distress; mysterious events in a graveyard or a temple; or having to defend a village or homestead from attack. What they have in common is that (i) they easily engage some fairly standard PC motivations (like protecting innocent people, preventing descration of a holy place, etc), and (ii) they invite a range of PC responses none of which is too likely to bring things to a dead-end (eg there are different ways to defend a homestead, both in terms of tactical preparation and also decisions about whether to sally forth, etc; and the attackes can also do things to try and lure the PCs out).
In my experience, the most common way for new GMs (and also experienced but not-so-good GMs) to kill the game is to have a preconceived conclusion or resolution in mind, and to try and short circuit play towards that outcome. Try to avoid that.
And a related point - I wouldn't encourage you to use opposition or antagonists that the PCs can't defeat, or that they can defeat only if they work out the particular solution that you as GM have written into the story. What counts as able to be defeated will be table-variable - at some tables that will mean fighting; other tables, which take social action as seriously as other types of conflict, will include outwitting or charming someone as a standard mode of defeat. At the first sort of table, I would discourage using (say) a local baron as an antagonist, because - if the gameworld is a typical one - low level PCs can't defeat a baron in a fight, given the baron's guards etc. At a table that takes social conflict seriously, then a baron can make a fine antagonist because while he is probably safe from attack he is certainly fair game for being tricked or persuaded!
But an antagonist who can be defeated only if the PCs learn the special secret and then collect the special ingredients is, in my view, a recipe for GM-driven railroading to a foregone conclusion and is a good way to kill the game. I wouldn't encourage that. Make your situation, and its resolution, open-ended. And then let your players dig into it.