The preposition 'à' corresponds (more or less) to 'at', so 'à la gare' is at the station, 'à l'école' is at school, 'à la maison' is at home, and so on. It can also mean 'to', so the question 'On va à la plage?' would be 'Should we go to the beach?' The preposition 'chez' refers to a person, for example 'chez toi' means 'your place' (your house/home' etc). It's often used for the name of a business, particularly a bar or restaurant - 'Chez Claude', for example, would be a place belonging to a restaurant-owner called Claude. 'Chez' also includes the concept of 'at' or 'to'. So, for example, 'Anne est chez elle' means 'Anne is at home', while 'On va chez Anne' means 'We're going to Anne's house.' Hope that helps.

You can use "à" to indicate where you are or the direction where you are going but when you talk about a place by referring to people, you must use "chez". Je vais à ta maison. = Je vais chez toi. Je vais au salon de coiffure. (au = à le) = Je vais chez le coiffeur. In this case native speakers use sometimes "au" but it should be considered as a mistake. Je vais au garage.= Je vais chez le garagiste. Give us tricky examples you don't understand.

For me, à should be used for a place, and chez for a person.