Do more of what works and do it better. That's how anyone can get more traffic, more leads, and more sales. Sometimes, this involves tearing up the box as it were as I will show you...
Doing articles? How can you do MORE and do it BETTER?
Buying co-registration leads? How do you scale it up? You would want to look into buying MULTIPLE campaigns at your co-registration provider, as can be done with Get Subscribers.
Signing up at a viral list builder like ListJoe or ViralURL? How do you scale your results through the backdoor? You would definitely want to consider buying MULTIPLE premium memberships so you can blast your ad out every day instead of every 3 days.
Doing pay per click? The answer would be hidden somewhere in these areas: more impressions, better Quality Score, more keywords, more clickthroughs.
Promoting an affiliate product and it converts? You might want to expand your marketing strategy to include other tactics you have not tried out.
Do it better and do more of it and squeeze out everything you can out of a strategy that works.