Forums and blogs aren’t there to only give out advices but they are also there for the webmasters to get visitors to their website as well. The point here is to help as much as possible so that it would attract people to check out the website of the webmaster.
No doubt that this will take time but after it is done regularly, webmasters will see that this becomes part of their daily habit. What is important here is to keep engage in an active way in these forums or blogs while giving out helpful information or comments and not just give out spams.
Adding the links to the website is actually easy. Blogs offer a column for the commenter’s website while forums have a feature called the signature. Users can write anything in the signature as long as they abide by the rule of the forum.
Bear in mind that constructive comments will be very much appreciated by the community and not spam. Therefore, if the webmaster cannot spend some time on forums or blogs, it is highly recommended for them to hire someone to do it instead but make sure that these people that are hired can give out excellent advices or helpful tips to the community.