If you have a relative or friend who is turning thirty you might want to celebrate with them, but are a little apprehensive to do so, as it is a large milestone age. Someone turning thirty years old may regret not doing something as a younger person, or they may feel like they are already too old to have fun anymore. People over thirty of course know that this is not true, but it will feel true. You might want to try a couple things to make the day as pleasant as possible.
The first thing you want to do is not mention the age of the person you are celebrating. The age of thirty is the age of being an adult, which can be a little stressful. This means that all the crazy things they did when they are younger are now banned from them, at least they are in their minds.
Anything childish is out, as they will not want to be reminded of how old they are. You can have a couple of stereotypical party things like streamers, and happy birthday posters, but party hats are not the kind of thing you want to use.
Having a favorite movie theme is usually a good choice, especially if the person you are throwing a party for is a nerdy person who really enjoys Star Trek or Star Wars, because those brands of shows have several kinds of merchandise and party supplies associated with them, and as long as they are not obviously for kids, it will be great to use them to dress up your party.
A cake is always something difficult for a birthday, but the best thing to do is get a practical cake without a lot of frills. This will not only save you money, because you usually can pull a pre-made one off of a rack, but also it will be a delicious treat without reminding them to much of it being their birthday.
Putting thirty candles on the cake is not only a bad idea because it could offend the person having a birthday, but also could cause a fire. If you insist on candles, put on one for symbolism, or three of them to represent each decade. Do not put on a candle with a large three and a large zero, as it will be staring them in the face, and make them remember that they are not in their twenties anymore.