The first order of business when planning a tournament is choosing when and where to host it. Be sure to pick a date that doesn't conflict with other events in your venue or other basketball games in the area. Many organizations have online calendars of events to help you plan. You should also consider the time of year you want to hold the tournament. If its purpose is to determine a league or geographical champion, then it should take place at the end of the season. If it's a contained event, such as an invitational tournament that simply declares its own winner, you can schedule it earlier in the season. Once you have the date, choose a venue and book it.
Now that you've got the event set, you'll need competitors. Who is this tournament for? Local youth teams? The adult rec league? Contact the teams, post registration instructions online and at schools, youth clubs, gyms and parks departments. Have teams formally register so you know exactly who's coming, and set a registration deadline far enough in advance to prepare the schedule. To make it easier, you may want to limit the number of teams allowed to play. And, of course, games can't be played if someone doesn't enforce the rules. So you'll also need to hire referees through a local officiating association.
Once you know who's coming, you can put together a schedule. Be sure to allot enough time each day to cover warm-ups and game time -- including halftime -- as well as extra room to stop the clock for things like time-outs and injuries.
In the weeks and days leading up to the event, you'll need to communicate with coaches, teams and volunteers about the logistical details. Also be sure to promote the tourney online and in the local press to generate interest.
People will need to eat throughout the day, so have a variety of food for sale. Remember that you're feeding athletes, so be sure to offer some healthy food and beverage options. If you're having a large tournament, think about selling T-shirts and other merchandise that participants and spectators can buy as souvenirs.
Remember the little details, too. Be sure to have awards for the winners, and don't forget to purchase extra insurance to cover liability.