There are many great college organizations that you can join. The larger the school, the more they might offer. The following are some of the common ones and tips on deciding which one to join.
If you like to play sports, then you might want to join an organization that is related to that. They have many clubs that are just for fun and you do not need to try out. These can help you stay in shape and get your daily exercise. If you like to be active and meet people who have the same interests, then this could be something you could consider. Think about your natural abilities and what you might find fun. You might find these revolving around the sports of baseball, basketball, flag football, karate, softball, soccer, etc.
Most schools usually have some sort of student government. If you like to lead and want to make a difference in your school, then you might want to consider this sort of organization. Sometimes there are positions to which you must be elected, but oftentimes you can work in some sort of capacity no matter what. This can also be great for your resume once you get out of school or if you are looking to get into graduate school. Also, if you live on campus, they may have a housing area council and have leadership opportunities related to that as well.
Organization related to your field of study
Often times there are groups and clubs related to your field of study. This can be great to join if you are interested in learning more about your field. It might be a good networking activity as well. This can be in all sorts of fields from science and math to history and engineering.
You may find an organization that is promoting a certain cause. If you feel very strongly about something then this might be for you. For instance, you may find an environmental action organization to join. They may have one that is affiliated with a particular political party. Think about what you believe in and whether you want to meet likeminded people and make a difference.
You will sometimes literally have hundreds of choices of college organizations from which to choose. Go down the list to decide which you might be interested in trying. The best way to narrow down the list might be to go for a couple of visits to see what you like.