Almost everyday I say. If you have new content on your forum or blog then that needs to be shared and viewed out there. Most forums and blog have social-media buttons and share options that gets tweeted right away, Just remember to use the right tags lol
On my end, I have an automatic feed that posts 10 a day on all social media sites.
FB can cost allot over time, but at least there they have a budget option on how much you want to spend each day. Just that for $5 a day do not expect to get much.True, you don't want to under-do it either. Anyway, though, on Facebook, at least, more than likely you're going to have to pay. However, the prices can be reasonable. One thing to take into mind is the audience.