Can someone point me in the right direction for learning about particle systems? Not the Documentation, or the pre-made samples. I’m looking for something someone in the community has made, or any other relevant information.
ImbueFX and 3DMotive have a great collections of tutorials. Not free however. They are really well explained and totally worht it. I already bought some of those and didn’t regret it. If you are starting, I suggest this one : https://www.3dmotive.com/f104301 (also available in download, not only streaming). More advanced particles :
https://www.imbuefx.com/downloads/category/udk/
As Philipp mention, what we have in UE4 is almost identical to what we had under UE3, so will be able to replicate the tutorial knowledge over the new version of cascade. There is maybe some effect that changed in names, and some material nodes too. Overall it shouldn’t be too hard to convert something from UE3 to UE4. 
ImbueFX recently added a 3 hour cascade and flip book creation tutorial on their Youtube channel.
For basic particles that are not specific for the UE4 you can also use the UDK tutorials from youtube
For other stuff → learning by doing
or when you like you can also add me at Skype, probably I can help you (nasph96)