I upvote articles of many different authors, especially also of new or not so well known members whose content I feel to be undervalued.
Some already "famous" writers automatically receive upvotes from many followers, bots and also members who hope to profit from curating popular stuff early enough (often independently from quality of the single article) so that within a few minutes they may reach a potential payout of 40 dollar or more. A newbie however may write a really long or creative article, but only gets a few cents. I try to balance that a little bit.

Of course I also vote for well known (and paid users) if I like what I see. I also try to support friends and people I like.
But all articles which I upvote have one thing in common: I do open, read and of course must like the content before I upvote them. :)
I only vote manually.

I resteem articles which I think are either of very high quality, useful for myself (in this case resteeming is kind of bookmarking them, too) or just very entertaining/funny to read.