To answer this I need to back up a little bit. Not all traffic is created equal, so how you got the traffic is of tremendous importance to the ability to convert that traffic.
Thinking of the various Marketing channels and placements as having a specific place in the Acquisition funnel of a client, some channels and placements might bring you traffic that is not yet ready to convert but is in need of, for instance, educational material. Other traffic is ready to sign up for an account right then and there. Yet again, other traffic is of such bad quality you wouldn't be able to convert it in any way. The key is segmentation, customized approaches to each type of traffic.
One of the rules of online marketing is to use landing pages to be able to offer a segmented experience, simple one-page websites with the key information for your target audience with one major call to action and, ideally, a form on the page itself. This type of experience gets a visitor to focus on what the action is that is required with minimal distraction versus, for instance, sending them to the homepage. Regardless, when designing your website you, ideally, take into account that every page on the site should be able to serve as a landing page in order to maximize conversion there, as well.
So for example you might have one landing page with a Trading for Dummies ebook offer, one with a guide to advanced technical analysis and one with a "sign up for a live account" offer. How do you know which to use and how to design them in the first place? If I am advertising on Google with the keyword "trading for dummies," it’s pretty obvious that traffic would convert best on the Trading for Dummies landing page, but in other cases it’s less clear. What to do?
This is where testing and optimization comes into play. By having a few different experiences (both in the advertisement and the corresponding landing page) that can be tested, you, in effect, segment your traffic by way of actual results. If clicks from a banner on Bloomberg.com convert best on the "guide to advanced technical analysis" landing page, you know very clearly that this traffic might require a more advanced experience. Clicks from a Google Adwords ad for your brand name plus "account" might convert best on a "sign up for a live account" offer. Further testing can then be done to refine the page more, itself, or to come up with new variations of a landing page; Continuous testing is the key. Tools like Optimizely or Unbounce might be helpful to do this on a regular basis.
Once the initial conversion has taken place, further marketing might be required to convert the trader to a fully funded live account; Besides sales efforts, marketing automation needs to play a large role in this – but I’ll leave that for another time.