Agree with above. Basics of BP control, electrolyte management, diabetes, treating uncomplicated infections, etc, will help you not annoy your medicine colleagues with basic consults or, worse, delay discharges due to non-neurological reasons. Knowing when a patient is "sick" has a subjective component that you learn with experience - you will have to recognize when things are headed the wrong direction before they actually get there.
Obviously mastering a quick H&P/consult note is important and something a lot of interns struggle with. Many med students can write an excellent/thorough note, but the challenge is writing 10 of them.
Other things to master: treating pain effectively (in neurology we don't just give everyone opioids), learning about systemic diseases with neurological manifestations, trying to learn a little rheumatology, and being able to assess someone from a musculoskeletal (in addition to neurological) perspective. This is just my opinion, but I'd try to get to the point where you can recognize basic abnormalities on various imaging modalities (e.g. broken bones, pneumonia, abscesses/masses, etc) yourself. This can be helpful overnight or when the radiologists are busy and reads are being delayed.