I've been in the internet marketing business for around 7 or 8 years (I've been online since the late '80's and spent way too much time either on BBSs or tinkering with hardware).
I've had quite a few successes online and an equal number of 'not-so-successes'. The key has been to just keep pushing forward no matter what the setback.
When it comes to a speciality I'm more of a jack-of-all-trades, and have a pretty good handle on most stuff. I'm loving the way technology is going right now.