If this is not a tournament at a poker club near your home, then you need to get a good night's sleep before the trip and eat well, but not too much. In all hands it is better to act approximately the same, not too fast and not too slow; try not to make any unnecessary movements that could give clues to your opponents about the strength of your cards. And maybe it’s better to wear dark glasses ))
I would also advise you to count the chips in pots yourself, because dealers can sometimes make mistakes. And it’s always better to put chips into the pot in one motion and declare a raise, otherwise your bet may be considered a call, preventing you from raising!