Vote for groups that don't have a strong lobby (youth, disabled, homeless, low-income people, the environment)
This should be self-explanatory.
These ballot props deserve a proper reading, but if you consider yourself a
democrat then you should probably go ahead and approve these measures.
Vote against things which infringe upon rights of the people
This rarely comes up, but it looks like: limits on speech, rolling back rights
(eg making gay marriage illegal again), limiting what people can consume or pay
We find propositions like this fundamentally illiberal. We should default to
more liberty and less central control of our lives.