I know that you can create backlinks in 2.0 websites, social network, forums... but building links in forum is the hardest but greatest. Why? - The link built in the forums can attract a great number organic visitors to your website. - The links are do-follow and google will rank your website due to these links But it is impossible for newbie to built link these because - You have to strictly follow the rule of the site owner. - Normally, the one who built single site PL will get banned very easily - You have to post at least 20 post in order to create backlink My advise here is you should get used to these forums before thinking of building backlink there. Be patient. Once you do, your website will extend very fast.
Sure - it would be best to have only natural links from other webmasters - but you have to start up somewhere. And the rule to get maybe not natural but not spammy links is best advice I guess.
If i may add, make sure that you have your target group and that the places will be used to build backlinks under your website will be for this specific target group. For example if you are selling web services you should try to find webmaster forums or websites related to hosting services.
Creating backlinks from forums are good! You should find relevant forums relevant to your business. Do not spam any forums, help other in the forums. People in the forums always looking for information than the marketing content. So your initial posts up to 100 (If you ask me), should have only informative content. It make the forum moderators to treat you as a GOLD member and they started thinking you as a best contributor. Stay calm, help others, you will get promoted/referred naturally by other members in the forum members.
Forum sites should have similar topics to your niche, otherwise your backlink will only make readers hate you)
building backlink in forum is really very hard because there are several types of rule for posting criteria and inserting a link in signature.
Well, you should build backlinks in forums relevant to your niche! In this case it should be easy to contribute something to the forums you want to build links in.