Welcome to the team, Christine!
I am also playing and GMing purely online at the moment. It is not so bad if you keep to some basic joint rules and reduce the group size, I found.
It begins with video during sessions and a video and sound check at the beginning, unobtrusive backgrounds and no eating with microphone on etc., also, for me a strong focus lies on interactions and less on maps (although my maps happen to become very intricate and detailed). And finally, rolling actual dice can be much more fun than clicking a button, but in case of some systems on foundry it is much easier to just click a button, so it depends on your players and style and system. There are several more rules in our group, but let's say these are the most important for us.
Johnn suggested a while ago to "dig deeper" when creating your world lore. By focusing on the characters first, you will definitely create a world centered around the PCs that will be much more appealing to players and will prevent you from focusing on aspects of the world that the PCs will never happen upon:
RPT Newsletter #499 | Turning Coal into Diamonds - How to Mine Backstories to Create Killer Campaigns
Regarding Story-Arcs, Johnn created some very nice courses on how to create adventures and campaigns in which he also talks about story arcs.
@JohnnFour, would you please post a link here again to these courses, in case Chrstine is interested?
Regarding Character-Arcs, I usually begin with surveying the characters and players and ask some questions.
- How do the PCs usually solve problems?
- What are the PC's goals?
- What are the player's goals?
- What could be an interesting twist and change of personality (hero story)?
- What could this lead to? And
- How can I create situations that put the PC into such moral dilemmas?
Combined, this can look like this (in my Expanded Treasure Table):
I hope this is immediately helpful to you. In case it is not or in case you have any other questions, please don't hesitate to post them. There are a lot of good GMs here that have many, many years of experience and each represent a very different kind of GMing. But that is the fun in it, I think.