Don't

Don't hide outline

Don't

  outline: 0;
  outline: none;

Do

  a.specific-class { color: #000; background-color: #fff;}
  a.specific-class:focus { color: #fff; background-color: #000;}
  a.specific-class:focus:hover { outline: none; }

Don't create fuzzy links

  <a href="http://some-url">Click here</a>

Don't forget the alt

  <a src="image.png">