With BitcoinTalk, you will need to have a BTC Signature. Then using it, you have to advertise a BTC product on your posts. You start earning money as soon as you hit 120 meaningful posts. A meaningful post is one with more than 60 words.
There are also weekly minimum and maximum posts. Generally, you can make at least 0.0005BTC per post. However, as you rise through the ranks, this can change to 0.144BTC per post. $64.08 per post doesn’t sound too bad, does it?