The following are thoughts on Buddhist ethics... brainstorming roughly... based on the first sections of Peter Harvey's book, "An Introduction to Buddhist Ethics."
To begin, worldview finds a central place in our examination of Buddhist ethics. How does a Buddhist look out upon the world and view him/herself in it? We are familiar with materialistic or hedonistic worldviews as well as Christian/theist worldviews. But Buddhism is neither of these. Instead it inherits and modifies the Brahmanic worldview of its time, based on the beliefs in karma and rebirth.
Our ethics, our way of living in the world, is largely determined by how we give meaning to the world and events in it, our beliefs, and our environment. For early Buddhists, this was a mix of pre-Buddhist beliefs and the new paradigm of the triple-gem: the Buddha, Dharma, and Sangha, to which one would "go to for refuge" upon entering the Buddhist path.
The Buddhist path represents a transformation between two other common terms in pan-Indian thought of the time: samsara (the cycle of rebirth) and nirvana (or moksha, liberation). And Buddhist ethics can be considered all of the ways of getting on and staying on that path, from cosmological stories to Vinaya injunctions to meditation and devotional activities.
Harvey (p.10) mentions the Kalama sutta, a famous (in the West) discourse that directs the reader toward his/her personal experience in conjunction with the teachings of wise people. Countless other teachings also give specific directions for finding one's way and staying on the path. Each of these must be taken into account as part of the greater whole of Buddhist ethics. This is opposed to many -mainly Western- attempts to reduce Buddhist ethics to some simple axiom or ideal. Such reductions, such as "end suffering," "achieve nirvana," or "cultivate love" may be possible, but they may not be terribly helpful. Thus, while catchy, they might not get us anywhere in understanding the many ways that Buddhists behave in the world today and in the past.
Some other key terms and themes to follow...