There are many expressions commonly used in English to express similarity.
There is no magic rule to help you remember them. You just have to learn them. Sorry!
Take a look at the examples below.
To watch someone / something like a hawk.
If someone watches another person like a hawk, they are watching very carefully and paying close attention, usually to make sure the other person does nothing wrong.
E.g. During the exam, the teachers were watching like hawks to make sure the children didn’t cheat.
Like lightning.
If someone does something like lightning, they do it extremely fast.
E.g. She ran like lightning all the way there to make sure she was first.
Have fun learning English!
Louise