[This page is necessarily incomplete. I will add items from time to time when I think of something.]
My beliefs are formed by the later 20th century german and middle european mainstream in which I grew up. While I do not share the faith per se, christian religion, especially in the northern-german lutheran variety, with some calvinist influences, is what shaped my thinking and ethics most.
Although I grew up with religious parents, I consider myself an agnostic in the sense that I not only do not know if a God exists, but also do not particularly care. Brecht's Herr Keuner advises someone to ponder if his behaviour would change if he knew there is a God, and if, he would need one; considering that, it looks like I do not need a god. In that sense I could say I am a lutheran-calvinist protestant borderline agnostic-atheist.
Most of my idea of human ethics can be subsumed under the Golden Rule "do not do to others what you don't want them to do to you", although I prefer the more positive form "treat others as you want to be treated yourself." This includes treating friends with company, good wine, and a game of cards, for instance.
In my opinion, the reality of man is for the most part a mental reality. While the physical reality exists and plays an important role, of course, the mental reality is more important because if a person happy or unhappy is a mental thing and most influenced by mental circumstances.
Material things can improve happyness by invoking positive feelings (for instance food and drink, a sailboat, a motorcycle) or enable one to do certain things. But for the latter the first examples that come to mind are a camera and a musical instrument, which both enable artistic activities, which belong to the mental reality again.
But mainly other people, and in particular the appearance of their mental reality are what influences a person's mental reality most. These are transmitted by various means of communication -- direct with smell, touch, facial expression, body language, speech, and other utterings, or indirect through recorded spoken or written language, pictures, movies, whatever. Consequently, communication is what shapes our reality most and what can make us most happy or unhappy. I am close to Paul Watzlawick in believing that our idea of reality is (mostly) based on communication.
Human rights are good. The freedom of one person should not be restricted except to avoid restricting the freedom of another more. Good idea, simple principle. Only it is immensely difficult to find the correct balance.
Democracy is good. Or, to paraphrase Churchill, it is actually bad, but we have nothing better. With democracy, as with freedom, it is infinitely difficult to find the right path. Politicians are doing a remarkably bad job at it, same as with other government issues. Unfortunately I have no hope I could do it any better myself nor am I sure I know anyone who could do it definitely better.
I like, to some degree, the idea of karma. Not that I think collecting good karma will give me a better next life (because I do not believe in rebirth), but I know it makes me feel better now. Related to that is the idea that when I do something good, this is not (so much) to make the world at large a better place some time in the future, but to make the world better here and now, even if only by a very small amount. And to make me feel better, too.