I disagree with the "policy" or guidance of this Meta question, if only because I feel any measurement of number of question upvotes vs. number of answers is a false metric.
Let's start with the guidance given to voters. The hover-over text for the upvote button is:
This questions shows research effort; it is useful and clear.
The hover-over text for the downvote button is:
This question does not show any research effort; it is unclear or not useful.
And from the Help Center's Why is voting important?:
Voting up a question or answer signals to the rest of the community that a post is interesting, well-researched, and useful, while voting down a post signals the opposite: that the post contains wrong information, is poorly researched, or fails to communicate information. The more that people vote on a post, the more certain future visitors can be of the quality of information contained within that post – not to mention that upvotes are a great way to thank the author of a good post for the time and effort put into writing it!
Now, just based on these guidances alone, I should probably be downvoting a lot more questions than I have so far, on the basis of "does not show any research effort". However, I realize that my judgment of peoples' internet search skills is probably skewed. For instance, we get a lot of questions where the answer is basically "Let me Google that for you" (LMGTFY), but without actually saying that. In cases like this, and in many others, the simple fact that an answer was given doesn't mean that the question is upvote-worthy, at least in my calculus.
(Having said the above, when it comes to personal practice, I mostly agree with you. I tend to upvote about 2/3 of questions I answer.)
If we were going to have a "policy" or guidance encouraging users to vote, I suggest the following instead: focus on earning the Electorate badge: Vote on 600 questions and 25% or more of total votes are on questions.
Now, I know a lot of people don't really care for badges, "internet points", and other similar meaningless digital clutter. But as a form of goal-based training, I think this one has a lot of benefit to the site. The process of obtaining the badge requires consistent effort, with only 30-40 votes per day. In doing so, and finding upvote-worthy questions, it forces you to go back through the history of Q&A's here. You become more familiar with the tone of the site, what kinds of questions get lots of love, what gets closed or downvoted, etc.
Additionally, I feel the process of seeking out questions to vote up helps to calibrate or discover the voter's own sense of what questions were upvote-worthy.
In short, chasing the Electorate badge made me a better, more knowledgable SE community member.