The new year is celebrated by prayer. Traditional foods include apples and honey which represent a good harvest and a sweet year. Some families get together for a special meal with extended family either on the evening that starts Rosh Hashana or after afternoon services at the end of the day. The meal is not part of the religious observance as it is with holidays like Pesach, but it is an enjoyable celebration for many families and friends. Many of the traditional foods have honey, tzimmes (cooked carrots with honey) or honey cake. Pomegranates are also a traditional food.
In 2018, Rosh Hashana will begin on the evening of September 9 and end on the evening of September 11. In 2019, it will begin on the evening of September 29 and end on the evening of October 1.
As with other types of new year or new beginning celebrations, many people like to take this as an opportunity to clean house. And some, wanting to begin with something good, start the year with a donation to their favorite charity.
Another tradition, and part of the services, is the blowing of the shofar. Some congregations record the sound and put it on a voice mail system, so that people who cannot make it to all the services or who want to hear the call of the shofar again, can call into the phone line and hear it.
Like with other, secular new years, many people make new year resolutions.
As with Shabbat, observant Jews will not work on the holiday. Although the definition of what constitutes work varies across different denominations.
Rosh Hashana is part of the Days of Awe. Many Jews who don't attend services all the time or even barely at all will attend them for Rosh Hashana and Yom Kippur. So attendance swells at many congregations. Some congregations have extra services, rent out larger halls, restrict attendance by using tickets (usually given for free to members, but sold to visitors). Umbrella Jewish organizations will help travelers or someone new to an area find a place to attend services. And some places advertise that no tickets or payment is necessary or that they have an "open door" policy. Other places will allow someone who is traveling or new to the area attend for free, but expect "repeat" guests to join or pay. And many congregations have plans to accommodate students or others without the income to pay for tickets. Some congregations require tickets for the most popular services or service times, but allow anyone to attend other services.
Because of the high demand for rabbis to lead services during the High Holidays, rabbinical schools have programs to connect their rabbinical and cantorial students with places that would like someone to lead a service -- usually smaller communities that cannot afford a full-time rabbi. This gives the student a chance to practice their new skills and provides a needed service for the communities.