Which are the best white hat techniques now?

[Sandara Bacon]

Posting in forums is not a black hat method, as long as you are not spamming it with useless ads/links which are not related to the topic.
If you are following the forums guidelines, and they permit a link or two in the signature in turn for quality posts, then there is no problem. Most of the members (if not all of them) are members in forums for this main reason: they can increase their inbound link counts thus increase their sites popularity and awareness...and perhaps also in order to make friends, relationships, but this is practically only a plus, an advantage. The main reason are definitely the backlinks.

One of the reason why most of Forum Site have a guidelines is to not allowing the spammers to spam the forum.

[SEOArbiter]

I agree with the former poster that off-page SEO is definitely the heart of SEO! White-hat SEO methods involve quality content that is regularly updated on your site along with daily links back to your site.