To promote fiverr gigs is to making people aware of you on fiverr. You are going to sale your expertise on fiverr. In all walks of life more you will be socialized more will be you successful. Likewise on fiverr. How people will know about your job if you will not tell them? Use Social networks to tell people that what can you do for them on fiverr. Do tweets to your followers. Create Facebook Fan page and post to your fans. Use Google and tell your friends.
The world is wide and you will find billions of people that are not aware of this network. This is best opportunity for you to get the word out. If you are really working by hear then you can avail this opportunity. Publicize your product and gig. You can promote yourself on Facebook and Google ad words. You will get more than you have spent on publicity.