It's better to install appium through command line, rather than just download appium, since appium GUI app is more fragile.
Make sure you have not installed Node or Appium with sudo, otherwise you’ll run into problems
rvm install ruby # install ruby and brew
brew install node # get node.js
npm install -g appium # get appium
npm install wd # get appium client
appium # start appium to see whether it works
To upgrade appium, you just need to run npm install -g appium
again.
For Android, we also need to install "ant" and "maven":
brew install ant
brew install maven