That's a big tragedy in our society, that you're expected to have a definite opinion on everything. Myself, I have very few strong opinions, and those that I have I hold loosely. When someone asks, I usually try to sketch the space within which I believe the answer lies (e.g. "I suspect X, but then there's Y and Z, and also V I'm not sure what to do with"). This has a nice side effect of making strongly-opinionated regulars suddenly unsure about their own opinions.
I am also this way by nature but it drives a lot of people nuts so I’ve learned to temper it for the particular audience, expressing confidence appropriate to the context of our shared assumptions.
I don't think the OP said that they have no opinion. Beliefs are a conviction based on cultural or personal faith, morality, or values. Opinions are viewpoints, we all have them, but it's good to be aware that they're not based on facts.
But how do you deal with the following situations?
-- talking to people, since you have no opinion
-- understanding the people around you , building a mental model of them
-- general confidence