"Do you need more than one Domain name?"
You need a site that is somewhat targeted to your niche, the more targeted the better and it helps if your main keywords are in the domain. So if you want to start promoting jogging strollers but your site is bestgolfclubs.com, then you may want to build a new site with jogging strollers in the domain.
Now that's said assuming you are doing niche marketing. A pro can build an everything but the kitchen sink, mall type site on a generic sounding domain like davesdeals.com, but that's a terribly hard way for a newbie to start.
You need a site that is somewhat targeted to your niche, the more targeted the better and it helps if your main keywords are in the domain. So if you want to start promoting jogging strollers but your site is bestgolfclubs.com, then you may want to build a new site with jogging strollers in the domain.
Now that's said assuming you are doing niche marketing. A pro can build an everything but the kitchen sink, mall type site on a generic sounding domain like davesdeals.com, but that's a terribly hard way for a newbie to start.