You can Visit the Famous Harminder Sahib Temple,Jallianwala Bagh,Wagah Atari Border,Kesar da dhaba (built before independence),you can try the famous dishes of Punjab (especially try Punjabi Lassi and Phirni).
Visit Golden temple, jallianwala bagh in one day. plan for wagah border the other day. rest days you can hop around at the famous eating joints of Amritsar and shop from various cultural galleries. Do try amritsari kulchas and shop phulkari
U can try Bharawan da dhaba, Kesar da dhaba, kulcha land. Also if you are a non vegetarian, u can try Beera chicken house and Makhan fish and chicken corner. On top of everything, don't forget to have the Langar ka prasad at Golden Temple. You can visit the market area surrounding the Golden temple along with Lawrence Road and hall bazar