What I’ve had the best success at takes some time and effort but engages a real audience. I join off-Fiverr forums related to my expertise. I don’t mention Fiverr or even use a signature at first. I try to become a member of those forum communities and offer advice, answer questions, etc.
After people know “me” then I gradually start adding my Fiverr profile in a signature. If that goes well (and is within their forum guidelines) I start adding little taglines like “Discounts to those who mention this forum in your first order or message!”
I find that I get more hits and better paying clients from those who already have interest in my subject matter, and even more so when they know I’m a real person. I get more out of 10 targeted contacts (which might turn into 3 paying customers) than I do from putting social media ads that are seen and ignored by 100 fast-moving Twitter followers. The paying targeted clients send me referrals too, leading to more sales.