This article is by request, 
Buying Steem Power helps you raise your voting power. It is an investment in Steem {STM} for a longer term. The value of Steem Power {SP} is the same as that of Steem. Moving Steem Power back into Steem takes 104 weeks, that is called Powering Down. In this post I'm going to focus on how to buy Steem Power, the easy way.
The most simple way to go about this is to use your build in Wallet at SteemIt dot com. There you will find a button that says: [BUY STEEM OR STEEM POWER] After that a pop-up will appear from where you can choose what to buy, Steem Power or Steem. By default this is set to Steem, so you need to click Steem Power first.
Then you have the choice how to buy the Steem Power. The build in exchange uses the 
You can choose which one with the 'Deposit using...' dropdown menu, this one defaults to Bitcoin. The specific data will be shown where to send the payment to, with Bitcoin and Ethereum that will be an address.
NOTE: For Bitshares there will also be a Memo presented that you need to use.
Which one you choose is up to you, but most of the time Bitcoin is being used. For the ease of use with mobile wallets, like CoinOmi/ CoPay/ SmartCoins, the QR-scancode comes in real handy, but only for sending Bitcoin.
When you want to know how much to send for an exact, more or less, amount of Steem Power you can use the [GET ESTIMATE] button. But you'll need to fill out the field below 'Estimate using...' with the value you want to send off course. This works two ways. It can calculate how much Bitcoin is needed to be send for a certain amount of Steem Power to receive. And how much Steem Power you will get if you send a certain amount of Bitcoin.
After you send your 'coin' it can take a while before the transaction gets confirmed and you'll receive the Steem Power in your Wallet at SteemIt dot com.
There are more ways than this to buy Steem Power. It is possible to use other 'coins' also using ShapeShift dot IO, for example. But that would be a little more complex than this.
This 'howto' was aimed at Steemers who are new to this subject and would like to get more Steem Power.
Have a nice one!