Easy! Many undergraduate and graduate students don't have anything even remotely resembling an office that they can tutor from. However, there are lots of places where you can meet students to help them with their courses. In face, some students prefer never to tutor in their office for a variety of reasons. Here are some other options:
Meet at the library. Most libraries provide the perfect combination of privacy, quiet, and comfort. There are usually several other people around so neither you nor the student is likely to feel alone and uncomfortable. At the same time, you don't have to listen to people constantly yelling, laughing, and running around. The logical choice.
Try the Student Union Building. Most universities have some meeting place for students with lots of desks, tables, and plenty of people. For students who work best with some atmosphere, this can be a great setup. Sometimes you have to tolerate other loud students or music playing in the background, but this is rarely a problem. This is a very non-threatening environment for both student and tutor.
Find an empty classroom. This is getting more and more difficult at many universities with the rampant cost-cutting in many education systems. If you find one, however, it can be one of the quietest places to work. In addition, classrooms often have blackboards and other tools you can use, if you feel more comfortable working in this way. Be aware that some students may be uncomfortable in a room with only the tutor. Try to leave the door open.
Over lunch or coffee? If the student just needs to discuss some general concepts, without going into any details, you can make the session very informal. Some students are more comfortable discussing things with other student in a relaxed setting. Obviously, there are many drawbacks to this, but it can be a nice change.
At your (or their) house. I really DO NOT recommend this. There is certainly potential for harassment with either of these options. Usually you're meeting with students that you have have never met. Use caution. Many tutors don't even give out their home number, instead using e-mail or their work number to avoid harassment and maintain some privacy.
Having your own office can make things really easy since students know where to find you, and you don't have to venture too far to help. However, there are many other more important factors which make a tutoring session successful. Make sure you know where you work best and ask for feedback from the students. The location you choose for a tutoring session can really affect how successful the session will be and how long it will take.