This kinds of links will harm your site so you have to avoid them in the future.
Google penalize this kind of links that are very easy to obtain :
1. Wordpress comments
2. Article directories
3. Forum profiles and signatures on low pagerank sites !!
4. Guest book comments.
So , this are the main kinds of links you should forget about !!
I was a big fan of forum profiles but now I will give up working on them . Not entirely , I will make a list of pr 4 and above or high authority edu and gov forums.
So let's see which are the links that I have tested and have results after this penguin update :
1. Edu and Gov links ( but not wordpress comments ) . Try to find Wiki's ( contextual links), high forum profiles, mooddle types, etc. Even wiki's are no follow I have ranked very well with it. I am simply in love with it!. I have a list with my own 14 edu blogs on different domains, where i build articles.
2. Sitewide links on high pr websites but not on that ones that have 100000 and more pages . I choose sites with lower number of pages.
3. Wiki sites : very good for rankings . I have huge lists , contact me at skype at : bradudan for details. Everybody says that wiki's are not important anymore cause they are no follow.
They forget that you should have no follow links too, to look as natural as possible . So contextual links on high pagerank wiki's sounds great.
4. Social media links : I have let them at the bottom cause this I consider that you know already ! It is obvoius that this are the top links . I personally promote every single url on every site to this high authority social media or bookmarking sites: Facebook, Twitter, Google Plus, Digg, Linkedin, Diigo, Reddit, Tumblr, Delicious, and of course Pinterest . There are many many more , you can use them with trust that will never harm your site .
5. Blog posts with contextual anchored links on as many as possible related blogs.
This kind of links are very very good for your rankins .
Private networks still works, and i might say that it works better than before Penguin update.
I have a 40 different domains private network with 1 x pr 4, 8 x pr 3, 11 x pr 2, 9 x pr 1 si 11 x pr 0 .
Some of them old and with high authorithy . i have built them on some different ip's on some different servers .
I put an unique article per each of them and have marvelous effects. I have to say that i do not build more than 2 links per article.
The websites are very different one from the others, built in time on some different structures, with unique content , very well done.
The idea of this post is to respond to those which says private networks are dead. Get a life men !!! IT STILL WORKS....
Right now i am working to have aprox 100 different domains until tha end of this year.
BE AWARE !!!
If you want to buy links on different websites be very carefull about it . Buy contextual links instead of footer or blogroll links. And be aware to number of indexed pages that tha website where you buy link have. I recommend websites with a low number of pages , but pagerank at least 2.
That is all with this tutorial , I hope you have understood the whole idea and you will have good and clean rankings. It is so simple but nobody have told you .
I know you feel that , I have had the same feeling when this idea came to me .
So in conclusion try not to give orders to Google but to listen what he tells you for good
rankings and you will see how easy it is to make your business and got Google respect for not being spammy .