Some cats do not like getting stroked from tail to head. Some cats enjoy it, but some don't, and if you're not used to being around cats, you're better off not experimenting unless you want to risk a bite or scratch. When cats are relaxed, they might roll onto their back and expose their belly. Don't always take this as an invitation to rub their tummy, as many cats don't like that at all. This is because in nature cats must be careful to protect themselves from potential predators (as opposed to dogs, who are more confident in this regard – and love having their bellies scratched). The stomach is a vulnerable area where all the vital organs are located, so lots of cats will instinctively bare teeth and claws if touched here.  Some cats do like it, but they interpret it as an invitation to play rough or wrestle with claw-grabbing and scratching. They'll wrap their claws around your hand or arm, bite it, and scratch at it vigorously with their front and back paws. This is not always an attack; it's how some cats "wrestle." If a cat grabs you with its paws, hold still and let the cat disengage his/her claws. If necessary, reach over with your other hand and gently pull the paw back to unhook the claws. Cats often scratch deep when they don't intend to if their claws get stuck. They use claws to hold and grab, so when the message is for you to stop moving your hand, they'll stop if you stop. Don't play with a cat's feet unless you know the cat well and know s/he likes having him/her feet played with. Start just by petting the cat to get him/her relaxed, then ask permission to stroke him/her feet by touching one foot once with your finger.  Many cats don't like their feet handled at all, but can be trained into it for activities like claw clipping through a slow, successive reward system.

TL;DR in Vietnamese:
Vuốt lông mèo từ đầu đến đuôi và không chuyển hướng. Không vỗ vào người mèo. Tránh xa phần bụng. Tiếp cận chân của mèo thật cẩn thận.