I've been in internet marketing since 2004. I was finally able to start doing it full time in 2007 and have been successful at it ever since. It takes awhile to learn and even then, nothing is guaranteed that you will succeed. The trick is: don't look for shortcuts.
Basically that would be the most important thing for us to do since if we look for short cuts on some matters then we would provably miss those critical information that maybe usefull on some aspects upon doing some strategy on advertising online. And Success rate for doing an internet marketing is depend on the people who works for that job and how they act decently upon executing it.