Get a table first!
Taipei's people put some clothing, a handbag, or umbrellas to mark their table before going to the counter and ordering their food.
It easily can happen to you as it so often happened to me that you enter a restaurant to see all the tables empty. In front of you a couple of customers who can't get their order out. The door opens behind you, opens, and open. You are noticing a line cuing up behind you. Now finally it's your turn to order and you got really hungry this time. Ready go I would like this that this and that! you pay the fast food goes onto the tray and you're standing there and nowhere to go all the tables and chairs have these markers. Lucky for you they were not dogs you can guess what I mean.
This is probably not the way people do in many other countries but they do it here and you will have to adapt. Put your umbrella where you want to sit first then order. When you go back to your own country read the book Nobody is Perfect to insure you’re not getting hit.