Whiteness as Lacking
Sissie often notices and comments upon how the white people, the white food, and the cold weather in Europe are less than impressive. In fact, their whiteness is more or less an absence of color, flavor, and soul; they are like wraiths, devoid of anything that makes them worthwhile. She concedes that whiteness has a strength within it though, and that that strength helped white people oppress Black people around the world. It is now a question of waking Black people up and helping them realize their own beauty and power.
Neocolonialism
African countries may have achieved independence from their European colonial overlords, but they still aren't completely free. Now they are embroiled in a neocolonial landscape in which European countries may not control them militarily but, instead, through indirect means such as their financial involvement and investments that keep them in a constant state of thrall. Many African leaders are themselves swayed by the promise of money and power and throw their own people under the bus as they try to get ahead, and Sissie sees the "been-tos" as part of the problem.
Been-tos
Aidoo coins a term for the Africans who went to Europe and then came back (especially only for short periods of time). She excoriates them for not wanting to do anything to help their people back home, for caring more about reputation and money and prestige, for doing their best to remain in Europe as long as they can and offering lackluster excuses as to why they need to do so.
Feminism
Through Sissie, Aidoo articulates a strong feminist consciousness, which is honed by the character's travels to Europe and her rumination on the ways in which women there and at home in Africa are oppressed by the patriarchy. Yet her comprehension of feminism is primarily an intersectional one and she does not have very much sympathy for Marija, the lonely German woman with whom she spends a great deal of time. Instead, she considers how African women are doubly oppressed by virtue of their race and gender and, by the end of the novel, has committed herself to exploring how to combat that.
Pan-Africanism
Aidoo also espouses a pan-African consciousness. The American Historical Association defines this as "the attempt to create a sense of brotherhood and collaboration among all people of African descent whether they lived inside or outside of Africa." We can see this in the novel in Sissie's initial observations of the conditions of African people in England and her growing sense of indignation and a need to unite them. We can also see this in her joining of the African student union, but unfortunately little is accomplished there due to their own shortsightedness. It is expected, though, that Sissie will work in this realm when she returns to Ghana.
Consciousness
Sissie goes on an archetypal journey from home to "exotic" locale to back home again. Along the way she comes to know herself better, situating her identity in a web of gender, race, nationality, education, and culture. She confronts some of her own biases (but remains blind to others), develops a feminist and pan-Africanist consciousness, and demonstrates a strong sense of self amid a circle of fellow Africans who call her a "killjoy" for giving voice to the serious problems in the way they approach their time in Europe and their obligations to their homeland.
Lesbianism
Marija tries to seduce Sissie and she is—at least she tells herself this—not interested. She rebuffs the woman's attempt and then treats her somewhat callously. It's not that Sissie is emphatically heterosexual, or that she finds Marija distasteful, or that she loves someone else; in fact, Sissie does imagine she is a man in a relationship with Marija and is tickled by the idea of power. It's rather that Aidoo suggests Africans have stubbornly maintained that homosexuality is a Western thing and that they are not ready to embrace it. It is complicated, for being like the West is problematic, but sexuality is not confined to a particular geographic region and for Africans to come into their own they'll need to embrace all facets of their identity.
