Legendarily, when the devil Mara challenged Buddha's great awakening, Buddha responded by simply touched the ground. Later, Buddha's first teachings addressed the human grounds of unnecessary suffering, rather than metaphysical or teleological issues such as the nature of things, or why things are as they are, beginning with his Four Noble Truths, that I paraphrase as:
The Four Noble Truths are a diagnosis, and the 8-Fold Path is the prescription; The Heart Sutra and the Metta Sutra also respectively diagnose and prescribe, but in more poetic terms, about a page each. You can find these and other Sutras easily by searching on the web.
Buddha's Middle Way balances between the opposites of ascetic austerities and self-indulgence. In his first sermon, Buddha reputedly said "There is addiction and indulgence of sense-pleasures; and there is addiction to self-mortification, which is painful, unworthy, and unprofitable ... the Middle Path (between these opposites) gives vision, gives knowledge, and leads to calm, to insight, to enlightenment and to Nirvana ... The Middle Path is just this Noble Eightfold Path ... "
Other principles of Buddhism include no self (anatta), transience and impermanence (anicca) and causation (karma), and emptiness (nirvana). No self means simply that beings and things are interdependent and changing; independent beings and things do not exist except in human imagination, i.e., in our mind's thinking and our communications including writing. Causation, or karma, implies that events happens due to prior causes and conditions. Impermanence means everything changes, including our egocentric notions of how things are, what this is, and who is. Emptiness defies logical interpretation; but is the truth of our experience, and even of physical energy/matter.
Buddhist practice engenders awakening and liberation. Buddhas awaken to unsurpassed, complete, perfect enlightenment, i.e., Buddha's enlightenment. Many of us experience gradual awakenings and increasing openness trom time to time in our practice, as well as a subtly increasing sense of transparency within ourselves and a sense of being increasingly permeated by the sweet energies of nature, nirvana, and emptiness.
There are many separate Buddhist organizations and/or lineages of Teachers, and they are quite diverse. Most are faith-based, like most western churches.
Among the most notable Buddhist Teachers, the Dalai Lama (Tibet) takes kindness as the core of Buddhism and happiness as the purpose of life. Perhaps equally notable, Thich Nhat Hahn (a French/Vietnamese teacher of Buddhism) emphasises mindfulness and practice; see my review of his book: "The Heart of Buddha's Teachings". Thich Naht Hahn's small book "Be Still and Know" includes "Peace is all around us, in the world and in nature, in our bodies and our spirits. Once we learn to touch this peace, we will be healed and transformed. It is not a matter of faith; it is a matter of practice." Peace is one Ideal among many, e.g., Truth, Love, Beauty, Compassion, Kindness, and Equanimity. Thich Naht Hahn's statement applies equally to each Ideal. Any Ideal can serve as your Ground for practice. Realizing and manifesting Ideals can be approached through practice.
Buddhism is relatively free of rules and beliefs. Instead Buddha urged students to rely on their own experience in deciding their practice. Practice in general can be described as what one does with respect to one's changing understandings of life's principles. "Spiritual practice is not some kind of striving to produce enlightenment, but an expression of the enlightenment already inherent in all things" (from Eihei Dogen's book "Beyond Thinking", edited by Kazuaki Tanahashi). Just after his enlightenment and attainment of Buddha nature, Buddha purportedly said "it is wonderful that all things, and all beings, are enlightenment".
Footnote: Evolution of Actionable Emotions: Many of our emotions evolved in our animal progenitors over millenia through mutations in genetic inheritance that proved advantageous in responding to nature's threats and opportunities. Discursive thoughts in humans are deeply influenced by partly unconscious emotions derived from evolution: felt actionable animalistic conclusions about situational threats and opportunities. Our thoughts (Freudian Ego) mediate between our egocentric desires/aversions (Freudian Id) and our ideals from social conditioning (Freudian Superego).
Dukkha can alternatively be translated as misalignment. Our ordinary experience includes dissatisfaction due largely to "misalignment" between our egocentricity and our true or original nature. Egocentricity is reinforced by delusions stemming from Habitual discursive thinking in part stimulated by correlated and partly subconscious emotions such as greed, envy, avarice, attachment and clinging, or anger, hatred, jealousy, anxious worry and pride.