UI/UX is a field I found myself thrown into thanks to the needs of a specific client and honestly, I just learnt on the job. If you understand graphic design and digital design (as in designing for digital platforms), then you should be able to jump into UI/UX fairly easily.
At it's basic forms, UI/UX is about making an interface as simple and as logical to understand as possible, even when it's a user's first time using the interface. Look at some shots on dribbble and you'll see patterns that emerge, such as certain icons being re-used, or grey being used for 'inactive' states of elements, because these are now ingrained in our minds as serving a particular purpose. To deviate from such foundations would cause confusion, so in this respect there are certain rules you can follow.
Honestly, it's really not much different from designing a website. You clearly present information and use hierarchy to control how a user interacts with a site. It's basically the same thing.