Here are my thoughts. So few people vote (compared to what would be ideal) that my method is this: If a question looks helpful in general, if not to you personally but it appears that it could help others, I upvote it. I end up upvoting the majority of the questions I come across (which is now 3,440 questions, out of the current total 4, 897). Even doing that, it's still a low voting site.
I think at this point, be free with votes. You are given 40 votes/day for a reason. Use as many as you can. As long as the post looks like it could help someone.
I also routinely scan for answers by new users and try to upvote them whenever possible. Try to reward whatever you can. I remember being warmly 'greeted' with upvotes and very friendly and encouraging comments when I joined in 2011, and that even before I understood really how the site was to work. Now I see more ignoring of new users posts. A click and a nice (welcoming/gently guiding) comment can make all the difference. For questions and answers.
Another thing I've found interesting is that if I average the score of my questions (142 total), the average score is 5.6., and I've accepted an answer on 99.97% of them. For my answers, (total 636) the average score is 3.4, with 54% of them accepted. So I find that at least for me, the questions are the ones that got the better welcome here, even though nearly all of them were filler questions I know the answers to, posted mainly for site activity. I found that somewhat odd.
I've seen the voting pick up in the recent weeks, and am seeing more participation from newer users, in voting. It's awesome. But we could still use more.