How can prevent bedbugs to not bite you?

In simple terms it is very difficult. The only real way is by preventing bedbugs infesting your home or having any bedbug infestation in your home exterminated. Because once they have infested a bed it can be almost impossible to stop them biting people in that home at night particularly when you sleep. And once one bed is infested they will move to other beds in same home. Unfortunately cleanliness is not a solution. All evidence suggests people who are spotlessly clean and have newly laundered bedding are just as likely to get bitten by bedbugs are people who are slovenly, dirty and whiff and sleep with unwashed bed linen.

Bedbugs are attracted to you by the CO2 you breathe out when you are asleep, and when any bedbug so detects somebody asleep it senses food. So, it will be attracted to the source of that breath looking for its food and once located climb in to the bed and on to that person's body, pierce their skin and suck their blood. Bedbugs most usually make their day time hiding place in the folds of mattresses, but they can be anywhere usually either in or near to a bed.