I would say forum posting is very useful for marketing and advertisement, you can advertise your services, your products and anything according to the niche of forums.
If you choose forum advertisement for your advertising needs, please make sure that you are contributing to the forums first, if you don’t contribute to the forum then you may be banned, this is very important thing to note.
Make sure you are not spamming forums as well, high quality forums are moderated and if you spam you won’t pass the moderation.
Forum Posting Service 