I don't know much about African Greys but from my experience with my lovebird Nibbles (RIP), talk softly to the bird, and just sit by his/her cage while you read or whatever and keep up the chatter. My bird bonded very quickly to me and thought i was her 'mate' which was quite funny at times African Greys are the most intelligent birds (besides Crows/Ravens). Maybe offer the bird his/her favourite treats like a piece of fruit or cracker. I think birds are like men, the quickest way to their heart is via their stomach .