On the plus side, you are getting some good traffic. The question is what type of traffic. Try to find out if bots are making up any percentage.

Also ensure your correctly identifying where you target market resides. People talk about penetration rates with broad campaigns with no focus. If you are operating within a specific niche whether it is language, geography, subject matter, then focus your marketing communications to services actively engaged by those niches. You may find a higher number of sign-ups with a much lower amount of traffic.

When it comes to messaging, survey existing users to determine what brought them to your site and why they signed up. This is a biased view but it is a starting point to understand key traits of successful conversions.