Take care of the medical side first. Dog bites carry a real risk of infection, and if the dog's vaccination status is unknown, rabies can be a concern — so get medical care promptly, even for a bite that looks minor. Prompt treatment also creates a record connecting the injury to the attack.
If you can do so safely, identify the dog and its owner, and get the owner's name, address, and any vaccination information, plus the names and numbers of any witnesses. Photograph your injuries and the location, and hold on to torn clothing. Report the bite to animal control, which creates an official record and can help establish the dog's history.
Finally, be careful about giving a recorded statement to the owner's insurer before you have advice — an early statement is often used to build a provocation defense or minimize your injuries. A free review can explain your options.