There are many ways that you can earn Steem Power on Steemit.com, but I’m guessing that you are looking for solutions that will give you the best results.
Let get out of the way methods that do not work that great, which are trying to upvote every new post that comes out to get curation rewards, commenting on new posts, commenting on whales’ posts in the hope they will go upvote your posts and other kissing xxx methods.
Now, this is what I do to increase my own Steem Power and it is growing at about 4 to 7 SP daily, and I’m just getting started.

Writing quality blog posts:
I just write one quality blog post daily that I upvote, and I upvote every comment made on the post to promote engagement.
I keep the default rewards of 50% in Steem Power and 50% in SBD, and I use all SBD to promote future posts with upvote bots.
Upvote bots:
I promote all of my posts with bots. I send from 10 to 20 SBD to several bots that will upvote my post and the rewards on the post may or may not cover the SBD paid, but the SP will be always more than not using bots. This is my main way to earn more SP at the moment.
You may want to read this article about Jerry Banfield’s bot: Promote Steem Posts and Fund Budget Proposals with Our Voting Bot!

Use this website to monitor bids and help you choose your bots: Steem Bot Tracker
Delegating Steem Power:
If you already have Steem Power, you can delegate it to a voting bot and earn daily STEEMand SBD. The Steem Power is still in your account, you just delegate the power to the bot and can revoke at any time. Keep a minimum of 50 SP for yourself.
This is what I am getting daily for delegating SP, and the more you delegate, the more you earn daily.

Read this post for more detail: New Automatic Daily Payouts of 60% APR for Steem Power Delegations!
Finally, I’d like to recommend this video by Jerry Banfield.