As a westerner, we do thing our own way and are not especially aware that some things we do might be offending to other culture. Taiwanese are more superstitious than us. Even if many things you might do wrong will for sure be forgiven by Taiwanese, you might find yourself in awkward situations that could be avoided by reading this article.
Do take off your shoes when entering someone’s home.

Do present money, a gift, a package or a document with both hands. It is polite to do so. It symbolizes that what you give is an extension of your person.
Do cover your mouth with your hands when using a toothpick in public.
Do compliment the food a lot. Taiwanese love to eat and are really proud of their cuisine. “Hen Hao Che” means delicious to eat in Mandarin, use it as often as you can
Do be super careful when crossing a road. As a pedestrian pay attention you have no right, even if a car should let you the way, they usually don’t do it.
Do stay on the right side of the escalator to leave the left side clear for those who wish to run down or up.
Do leave the dark blue seat in the MRT unoccupied. They are reserved for people in need (elderly, pregnant women, people with toddlers, etc.)
Do not eat, chew gum or even drink water in the MRT
Do not speak about ‘death’ or the number ‘4’ (which has the same pronunciation as death in Mandarin, Taiwanese and Japanese) in place like hospitals. Taiwanese are quite superstitious and would be offended by your saying. Most buildings don’t have a fourth floor for the same reason.
Do not open a present in front of the person who gave it to you
Do not stick a business card you just received in your hip pocket (nor in your wallet then in your hip pocket). The person who gave it to you might be offended by your act meaning you want to sit on them. Putting it in the front pocket is however not offending. It is also best to read it, showing interest in what the person does, before sticking it to your wallet.
Do not wave at someone to come to you with your fingers turned up, wave with down turned fingers.
Do not leave your chopsticks upright in a bowl with left overs. This is offensive as this symbolizes offerings to the dead. You’ll often see sticks sticked into bowls when visiting temples. But doing so in a restaurant is a terrible curse on the proprietor.
Do not throw away your receipts (the first ticket with the QR code on it). Indeed, you might throw away the jackpot. Since receipts in Taiwan are part of the Taiwan Receipt Lottery. Every two months they release the numbers of the winning tickets and you can win millions of NT. You just have to check the winning ticket numbers on the website (in Chinese of course) or scan the QR code with an app. It takes time to do it, but if you win, it is worth it.