Depends on the Communist Party, but most work for current reforms and work with activist groups on the ground.

Other times, they may field their own candidates or they may endorse lower-ranking or leftist candidates, since they are political parties, and it generally behooves them to participate in elections of some sort.

Often times, you'll find Communist Party members in the labor movement, depending on the Communist Party and their history.

Mutual aid may also be done.

One of the main objects is to accrue goodwill in order to develop the struggle in a positive direction and to a higher level and to create "dual power," forming the ground for an eventual revolution of some sort, whether that be democratic or then socialist.