Answer:
The biggest challenges in making money online is learning exactly what you have to do to make it happen. What I mean is that there is so much information about making money online it is very easy to get information overload and become paralyzed. There are also way too many scammers just wanting your money. Weeding the good from the bad can be tedious and time consuming.
If you have no Internet marketing experience and don't have time to sort through all of the available information, you really need some guidance from someone who has done it before. I would recommend you take a look at WarriorForum.com. That is a great site with a ton of free information. You can also take a look at this free video series that goes through all of the parts of building a web business. http://bit.ly/webbizexplainedvideos.