Call your doctor first and consult with them, if it is necessary for you to come in person. Try to avoid places with an increased risk of infection.
If possible, travel by car or call a taxi. Only stay in the waiting room for the necessary time and keep the distances between other patients.
Of course, cover your mouth and nose with a respirator without exhalation valve or another personal protection equipment article with at least 94% filtration ability (FFP2 or KN95 class). Avoid touching objects that have been touched by patients before you (such as handles, railings).
However, do not underestimate the importance of preventive health checkups!