찾아가다 is going somewhere on purpose to find it or find someone, where plain 가다 is just going. -고 gives what you did first, and here that is nearly always your homework: 다 리뷰 보고 찾아가니까 'I go after reading all the reviews', 전화를 드리고 찾아가서 'called ahead and then went', 설명 이렇게 잘 듣고 찾아가시면 돼요.