Do I need to make appointment? Or is it first come first serve?

Generally you dont make an appointment. You get a ticket from the machine and priority depends on what reason you have come and how many people are waiting for that service. I find it pays to get there 10-15 mind before opening and often out by 9:20am.

What Xristos said. Only I will add that you can make appointments and by doing that you will save yourself a lot of time