- Use http://yaml-online-parser.appspot.com/ to make sure it is valid yaml.
  http://lint.travis-ci.org/ is recommended elsewhere but does not give helpful
  error reports.
- Make sure all of your "-" lines start on the same column
- Use bash scripts for `before_install` and `script` or any part that
  has conditional statements
   - Make sure they are "executable" (chmod +x)
   - Use the following header:

   ```
     #!/usr/bin/env bash
     set -ex
   ```

- Use `travis_retry` before a command to have it try several times before
failing (useful for installing from third party sources).  Note that this
command is not available within a bash script.
- Feel free to cancel a build rather than waiting for it to go to completion
  if you have made a change to that branch.
- A VM with 64bit Ubuntu 12.04 is a huge help for debugging.