The first Paramita (see The Ten Paramitas) is Dana, or generosity, especially generosity of spirit. Some of the situations in which we fail in being generous may include:
Stubbornly insisting on having things our own way
Not respecting others; not listening with an open heart/mind
Not answering questions; defying social expectations (How are you? What do you do?)
Not accepting invitations
Not teaching (but, remember Upaya, skillful means)
Not offering the Three Refuges
Of special note are 4 and 5. Is it always more blessed to give than to receive? If so, the generous act is to graciously receive so the other may be blessed by giving.