This site is super useful, it shows what your voting power is, also who has been upvoting your posts, what your rewards will be and how your posts are preforming.

It is recommended that you allow your voting power to build all the way up to 100%, and use maybe 40 or so votes per day, that way your vote keeps most of it's value.
Not sure how much you have read of the FAQ page, I have read it over a few times, still making sense of it.
From what I understand, when your vote power is closer to 100% then you get more rewards for voting on posts, which the earlier you vote on it, the larger your reward.