see our article on killer icon design tips. It's worth noting that sometimes, a symbol logo can be used as an icon.
If you're looking for more design trends, take a look at why so many brands ditching their logo in favour of iconic typography.
Rob Janoff, designer of the iconic Apple logo, reveals that the bite in the apple was added for clarity and was not a reference to the computing term 'byte', Bible's forbidden fruit or Newton's legacy ...