First question: how did you set that goal of 500 visitors per day? What do you believe will happen if you hit that goal? And why are you focusing on traffic and not on sales?
See, there are any number of ways you can get hundreds, perhaps even thousands of visitors through your site. But unless those visitors are targeted, prepared-to-purchase customers, all the traffic in the world won't help. Traffic without sales is just a waste of bandwidth.
Getting more traffic often requires the cooperation of other websites -- getting sites like search engines to send you visitors, for instance. It's hard work, at least some of it is out of your control and/or expensive, and it could all go away -- poof! -- in an instant (say, if for some reason the search engines decide to de-list your site for some reason, or there's a glitch in the search results).
Increasing your conversion rate, on the other hand, is almost entirely under your control. It has to do with the content and copy on your pages, your site navigation and architecture, the checkout process, the appearance of your pages. It's just as hard work as getting more traffic, but if done right it's more of a sure thing and will pay dividends for a long time to come.
Lots of websites convert fewer than 2% of their visitors to customers. Many convert fewer than 1%! If you can double your conversion rate, you double your sales -- without increasing your traffic at all.
I know this doesn't directly answer your question, but if I were in your place I'd be focusing more on how many sales per month you need to turn a profit, rather than just on raw traffic numbers. Then analyze your site to see where you're losing visitors, and target those areas for improvement.
You just may find you can reach your business goals with a lot fewer than 500 visitors per day.