Is it better not to negative things in the conversation?

I don't think that not being honest is the best route to go. There are always tactful ways to express your likes and dislikes. Once you have learned how to do that, you will be ahead of the game. Always stay true to yourself. Never try and be someone your not. Hmmm can I find anymore cliches? ;) I'm serious though, just be you. I hope this has helped.