In the cryptocurrency community, whales are known as those who are large holders of a particular token. I will explain why it is to your advantage to know which accounts are the large account holders of Steem Power and to vote with this knowledge in hand so as to maximize rewards for upvoting.
The Steem network bases payouts to users for votes based on
the order of the vote, and
the amount of voting power that is used during that vote.
Now, the reason you want to know which users have the largest amount of Steem power is due to the fact that the rewarding algorithm for (and from) upvotes grows superlinearly as voting power increases. This is to prevent what is known as a Sybil Attack.
Without going into the mathematical detail, what this means to the average Steemian is that
higher rewards are obtained when power is accumulated into one account. In other words, for the same cost, a larger payout is obtained when the same voting power is not distributed, assuming all else being equal.
Whales have an incentive to use their voting power to upvote content they like so as to obtain rewards from the network. Since whales, by definition, have a lot of voting power, it makes sense for you to follow them and to anticipate their movements.
One simple way is to autovote a whale's posts. This can be done using tools like @complexring's Autovote Bot. Likewise, if you are following someone with a lot of power, it is a good chance that others are as well. If you vote for content before other users, this increases your reward from the network.
However, do not vote too often! Your voting power, and the rewards that you obtain from an upvote, is governed by a mathematical equation. Essentially, your voting power is decreased every time you vote (up or down). Your voting power will completely replenish after 24 hours of non-voting.
Note that this means the replenishment does not occur at a constant rate. That is to say, your voting power increases more quickly when it is closer to 0 percent than when it is closer to 100 percent. In fact, your voting power will increase two times as fast if it is at 50% than when it is at 75%.
On the other hand, since rewards are based on the amount of voting power at the time of the vote, upvoting content when your voting power is at 75% than when it is at 50% will yield higher rewards.
This leads us to define a fundamental rule in upvoting content if you want to maximize rewards and you are not at maximal voting power: The order in which you vote the content that you like matters!
The other strategy mentioned is to anticipate the vote of large Steem Power holders or whales. Since other users are also incentivized to upvote content, and, in particular, so are large Steem Power holders, you can use this knowledge to your advantage and try to guess a whale's upvote. The first method mentioned was to autovote a whale's post. However, there is another alternative.
This other option is to vote for quality content that you think is a hidden gem and has the potential for being upvoted by a whale.
Finding quality content and upvoting it before a whale comes along has the potential to be far more rewarding. This requires you to constantly update a list of authors who produce top-notch content but are not currently being recognized for their contributions. On the other hand, you can sometimes find an overlooked post or comment written by a quality author.