improve OSX instructions

README.md

@@ -12,11 +12,18 @@ Demo video [in this tweet](https://twitter.com/bert_hu_bert/status/1561466204602
 [Blog post with more videos](https://berthub.eu/articles/posts/tracker-beeper/)
 
 ## Installing on OSX:
+If need be, install Homebrew via https://brew.sh/ as this will allow you to
+compile new software. To do so, copy paste the instruction under 'Install
+Homebrew' into the terminal app. This might take quite a while.
+
+Then run:
 ```
 brew tap robertjakub/teller
 brew install --HEAD googerteller
 sudo tcpdump -nql | teller
 ```
+And it should work.
+
 
 ## How to compile
 This will currently only work on Unix derived systems (like Linux, OSX and