Using Taro as a primary example, this video gives the basic rules of Gift-Giving in Sunshine Islands. In many respects, it may be useful to players of Island of Happiness as well, although there are differences between the two games, mainly in terms of the rewards for Gifts and increased Friendship Levels.
Characters who appear in both games do tend to have the same likes and dislikes in both. Taro is a pivotal Character in Island of Happiness as it is he who will give your Character his/her Fishing Rod. In both games, speaking to him each morning will give your Character an infallible prediction of the weather for the next day.
N.B. I usually publish the link to the actual video as soon as it is created by YouTube, but often the video has not been processed fully at that point in time. If you try to access the video and receive a message to the effect that it is 'unavailable', it simply means that YouTube has not processed it completely yet. Wait half an hour, then try again. Thanks!