Read Sri Aurobindo's 10 upanishads. Nothing can be better than that. He was not only a good author but a Highly accomplished Yogi. He understood first hand what he was saying. Indians consider him as a Rishi, sage, seer; the same as the authors of the Upanishads.
Read the translation of
Swami Sishya Samvad if you can find one. Dialogues between the Master and Disciple. The master being the great Yogi Swami Vivekananda and disciple Saratchandra Chakraborty. Its
philosophy in motion and the language is just like me and you conversing! Its that simple! The english name is "Talks with Swami Vivekananda".