The PDF copy of #CastlesAndCrusades player's handbook is available for free from the Troll Lord Games website here https://trolllord.com/product/castles-crusades-players-handbook/.
TV Tropes is great for teasing out story ideas. I've found that once I understand basic story structure, it's a lot easier to make small changes to keep players involved in a familiar plot but with enough twist to keep them interested.
When running a published module, I've been lucky enough to find digital copies of maps available with a quick search. Drop it into a chat service (our group uses Element, another free resource!) to show players the lay of the land without having to draw out details. Use a browser with a screen capture and you can drop specific snippets and cut out spoilers.
The above mentioned Element is great for keeping individual channels for game chat, sharing spells or pictures of characters and monsters ad well as maps, and can host calls for online games.
Youtube can be great for finding playlists or specific pieces of music or clips for background atmosphere or show off what your scene would look like.



