The best way to avoid crowds at popular attractions in Rome is to plan your visit in the off-season, usually from November to March, when there are fewer tourists. Another option is to visit in the early morning or late afternoon, when tour groups have not yet arrived or have already left. Book your tickets online in advance to avoid queues, and visit lesser-known sights rather than the most crowded ones. Walking to the sights instead of taking public transportation can also help you avoid crowds.