1.Downline building programs for PTC sites.
They will help you get referrals and earn money.
PTC referrals is one of the best downline building programs for PTC sites.
You can read more Here
2.Forums
Place referral links in your signature, Create a post containing your referral links, and Link the "www" under your avatar to your forum post, now every time you write a response the signature well placed automatic ander your response. don't try to add links to your response because than you going to be a "spamer" and spamers get bend from all forums.
you can find a lot of forums that related to ptc issues Here
3.Blogs/Websites
With this, all you do is create a blog and post your referral links on there, now you can advertise your blog or website anywhere you can from your forums, ptc sites ads... to attract visitors.
4.Email
Send an email to everyone you know who might like the PTC idea or want to find additional ptc sites. don't go spamming people! use appropriate etiquette to all people you send your emails!
5.Recommend people you know
This might not be the best of ideas or appropriate in some situations but if you know some people out there who might like the idea of PTC then tell them about it and maybe tell them about your blog, website, forum post etc...
6.Live chat programs
advertising your referrals in online chat rooms and IM programs, you can get a lot of peoples attention but again make sure you use the appropriate etiquette and your not breaking rules by spamming etc.
7.Advertising in the real world
create flyer's and distribute them on public notice boards, hand to hand, advertising in newspapers, local newspaper and so on... make sure its appropriate and you obey any laws in your area etc...
8.advertise on PTC and other types of sites
advertising using ptc sites, make sure that you dont advertising in the same ptc site that you are try to get Referrals becuse people that see your ad is already registered to the same site.
Good luck to You!!!