Higher Music is a breeze, I thought anyway. Just a bit longer time for practical and the concepts are relatively easy to get your head around. I think there around 30(ish) that you need to know.
Higher English is also relatively straightforward. You get a bit more time to answer a slightly harder question. The Higher English critical reading is more of a direct question, whereas national 5 is like, write about a book. Also, the close reading, or reading for UAE, the focus is more on the analysis, so ensure that if something is worth 4 marks, write at least 4 things! I always wrote one more just incase.
Higher Modern Studies is basically common sense. The only thing you may find a bit difficult is remembering the examples to use. And your 20 marker has got to be in the world issue (Africa) section this year.
From what I've heard from people who re-sat National 5 maths is that the second time around it's much easier as it's more repetitive if that makes sense. ie. You have already done the course, so going over it again makes it sink in a bit more.
Hope that helps! However, remember to keep on top of your subjects. Theres a lot more in a Higher Course than National 5.