How to trust someone?

this is a very common issue that most people have...the only real good advice that i can give you is you cant live your life not opening up to anyone even though it might be hard because of your past experiences but life goes on"if u don't allow your self to open up to anyone u will live your life being miserably dis honest to any one if u continue to live this way it will only make people not wanna be honest with u and not wanna Trust u because in a friendship or relationship this should always be 50/50 and if u continue to not be honest and open up a little no one wants to be around u or even talk to you because they know from the beginning you wear going to not be true... i am not saying telling the whole world your business but its ok to open up.. in this world people get lied to and betrayed but that's all apart of life to live and learn don't let p experiences block your future..