How to convert steemit to USD

Steem is a very young currency and as such you will need to follow a few steps to convert Steem to your local currency:

1 - Earn enough Steem on steemit.com or via mining
2 - Transfer your Steem to a Steem exchange and convert to Bitcoin
3 - Transfer your Bitcoins to a Bitcoin exchange
4 - Once you are fully registered at the exchange you can convert your Steem to your local currency and transfer to your bank account

Earn enough Steem
As the front page of steemit.com mentions with "Get 3$ Steem Power when you sign up" each new Steem member gets 10 Steem as a reward for joining the community.

You can see how much steem you currently have by clicking on your wallet. However, you cannot cash out your Steem until you have own at least 100 Steem and must wait until the 4th of July. This measure exists in order to prevent an abuse of the system e.g. by signing up multiple times.

Transfer your Steem to a Steem exchange
Once you own enough Steem you can transfer it to an exchange. CoinMarketCap is a respected institution for reporting volume of crypto coins on exchanges. Here you can see where most of the Steem is currently traded. I recommend to pick an exchange with the most volume as it will allow you to trade Steem with the most liquidity (at the time of writing Bittrex). There also exists other ways to convert Steem to Bitcoin e.g. via Blockpay or Blocktrades.us.

Transfer your Bitcoins to a Bitcoin exchange
Steem at the moment Steem can only be traded into Bitcoin. You will need to convert your Bitcoin into your local currency by using a Bitcoin exchange.
The biggest exchange by volume are at the moment Bitfinex for USD and Kraken / Bitstamp for EUR. Usually you will need to provide proof of identity and address to these exchanges before you can convert Bitcoin or payout your currency to your bank account.
Source : https://steemit.com/steem/@riensen/how-to-convert-steem-to-usd-eur