Some people fixate on making money from how they curate and vote. I personally think this is a bad idea and it also doesn't really work too well unless you have a lot of steem power.

I believe a lot of the trending being so often the same things over and over again is sometimes people piling on "popular" posts hoping to improve their curation rewards.

If you have a lot of power then curation rewards do matter some.

Otherwise you'll make more just finding things to write and share about that you are truly interested and knowledgeable about.

As to your vote. I can tell you what I do. As far as posts. I vote on things that I either want to see more of, they engaged my mind in some way, or I can see a lot of effort went into it.

So vote on the things you want to encourage and see more of. That seems more important to me than trying to maximize your tiny curation rewards.

As to resteeming. When it was implemented I personally made a statement that I was going to try to treat resteems like posts. I did this not because I have to, but so I wouldn't spam my followers.

So I try to shoot for 4 or less per day, though I am okay going up to 6. I've maybe done 7 once or twice in a year of being here. This is my personal system.

You will need to find what works for you. :)