"I'm continually amazed by how much better people react if I remember to arbitrarily throw "I think" before I state an opinion. I mean, it's coming out of my mouth, and it's not like there's some external arbiter of which sitcom is funniest, so of course it's an "I think." That's assumed. But, apparently, if I go out of my way to remind people that it's my opinion with a marker that makes little sense to me, they relax. So I do it."
A lesson I have only recently learned in my 30s, it really does help!