Don't worry if you don't have a fancy telescope. No matter how modest it is, it is most certainly better than the one that Galileo had to work with. An experienced astronomer can help you find objects within reach of your scope. If you are thinking about getting a telescope someday, that's an even better reason to attend. Star parties offer the opportunity to compare commercial or home-built equipment.
Amateurs are usually quite eager to give verdicts on the performance of the items they've bought.
It is impossible to have fun at a star party if you are cold. As you will be standing or sitting much of the time, you won't be as warm as you would be if you were out for a brisk walk. Dress warm in layers. Bring more clothes than you think you will need. Many people have left a star party earlier than they wanted to because they just got too cold.