At the risk of sounding overly pedantic (instead of just plain pedantic), Julia's response is spot-on and one of the things most new players have to contend with, beyond the overall complexity of the rules is that FFG is in desparate need (or at least was in desparate need) of an editor. Terms that are poorly defined in the game include: location (does it include Other Worlds, Street Areas, and/or the actual circular places on the mapboard), spend (is it a 'cost' or a 'loss' as each one has a particular meaning in the game), and others. I'm sure someone has created a Top 10 List of items every new player should know, but the three that come immediately to mind include:
1. Follow the Phases ~ that will solve most of the issues you encounter.
2. Take note of what you can actually trade ~ it's a long list but does NOT include Monster and Gate Trophies, nor Clue tokens.
3. You cannot be double delayed, double cursed, double blessed, etc. The conditions are binary..you are or you are not. If you are Cursed and receive another Curse, you simply do not roll to discard it during the next Turn's Upkeep Phase.
FFG recently released a 40+ page FAQ after many years of work, BGG has over 578 "pages" dedicated to the base game alone…there were and are many questions, but fortunately the types of things that can derail a game because of these questions are few and far between, once you have the basics covered. More than anything else, enjoy the game ~ Arham Horror is all about the journey, not the destination.