We can't force people to vote. There is no way to do it. No SE site has found a way, anyway.
I have my own set of rules in regard to voting:
- if I answer a question, I always vote. If I decide to "dignify" a question with an answer, I "dignify" it with a vote. Here on parenting it's always an upvote, not always so on SO.
- if I can understand the question immediately, I almost always eventually deem it worth upvoting. Short, simple questions are often the best questions
- questions difficult to understand deserve to be "put on hold". I don't usually downvote if I don't know what the question is about - but a temporary closure intil the question's problems are resolved works well.
- bad formatting and lack of puctuation marks is often a good hint for a downvote. If someone doesn't take the time to write the question properly, he usually doesn't take time to think it over. Many bad questions are terribly spelled.