First, when you upvote someone's post, it costs you nothing. You don't have to give that person any of your STEEM, STEEM Dollars or STEEM Power. The value of your vote is determined by your STEEM Power, the more STEEM Power you have, the more your vote is worth. And not only does the person you vote for get paid, you get paid. So if you have a lot of STEEM Power it is in your own personal best interest to upvote as many good posts as you can, which will in turn make others with high STEEM Power take a second look and maybe vote for it too. 50% of a posts reward goes to voters, and 50% goes to the poster, if it is a comment then the second 50% gets divided up 25%/25% between the commenter and the original poster. You can see this system working in the wallet of one of steemit's creators here:
https://steemit.com/@dantheman/transfers (go to the bottom to see Curation/Vote rewards)
People with high STEEM Power also receive interest at a rate of about 12% per year, meaning that their STEEM Power and STEEM goes up without having to do anything at all. Then as they vote for posts and comments they get even more STEEM Power and STEEM. Then as they post and comment themselves, they earn even more STEEM Power and STEEM. You want to vote on at least 20 posts per day, because your Voting payout is divided by the amount of votes you make, but no matter what it will be divided by 20 if you vote for 20 or less. So might as well vote for 20 so that there is a higher number being divided by 20 rather than a small number being divided by 20. And that division and payout happens every 24 hours.
This has only been happening for a few months, so there are very few people with a lot of STEEM Power. But by this time next year, there will most likely be hundreds or even thousands of people with high STEEM Power, meaning that they will be able to Vote and give higher rewards for posts, as well as receive higher rewards for upvoting/curating posts, and eventually there will be hundreds of thousands of people with high STEEM Power. Right now you may notice on the trending page that there are usually a few posts that hover around $1000 and those are the highest valued posts, but within a year a normal post on the top of the trending page will most likely have $10,000+ awarded to it. And when you vote on a post when it is still in the beginning stages and has not been upvoted by very many people, you will get paid more than anyone else when it gets all its votes, so look for content that you think will get a lot of votes. If you have high STEEM Power, you could actually influence future votes on a post simply by putting your vote on a post first.
For the next month or so it will be hard to get good payouts, as there is an influx of new users and a shortage of people with high STEEM Power. But as the new people begin to invest in STEEM Power, and slowly build STEEM by posting content and earning small amounts, eventually it will become easier than it has ever been to get high payouts.
The page that shows the users with the highest STEEM Power is called the Rich List Here is a link:
https://steemd.com/richlist
If you believe in STEEM and Steemit, and have a few extra Bitcoins or money to spend on Bitcoins. Now would be the time to Power up and start earning voting rewards and interest. Your STEEM Power can not be converted back to STEEM, and therefor can not be converted back to Bitcoins for 2 years and interest can only be collected on STEEM Power you have already. So the sooner the better.