Two things I tell any new marketer that asks. First of all, get your head out of your rear end. Drop all the dreams of working for 3-4 hours a week while living on the beach watching thousands of dollars pour in to your bank account. If you want to succeed in online marketing, you have to treat it like a "real job". You have to put in the hours. You have to hold yourself accountable to deadlines and goals. I have never met a successful internet marketer that got there by barely working. Hell, I work more hours now than I did when I had a "real job". It's flexible, and I can take off when I want. But I work.
Second, focus 90% of your efforts on generating traffic. Most internet marketers fail because they spend weeks or even months building and tweaking the perfect site. They have to have their content just right. The website has to layout perfectly on 75 different browsers. They must build the best autoresponder email series ever.
They do all this, and then nobody visits their site. They get frustrated and quit.
Screw all that stuff. You can build a site that is mostly crap and still make money if you flood it with traffic. Figure out the traffic side first, then you can worry about improving conversions and generating more sales. If there is no traffic, it does not matter how good your site is.