There are many strategies to power up. Writing great content is free but nowadays the price of Steem is such that payouts contain 6 times less SP than the number of SBD. There used to be a time when SP payout was more than SBD payout (SBD and Steem were below $1 and Steem was cheaper).
But that time is gone. I am posting a complete guide on MinnowBooster today which contains a good detail on how to lease SP and increase your SP via the leased one.
If you ever find Steem near $1 to $2 mark again, power up tons of it.