Peace be upon you. First, before you begin studying philosophy, it is essential to familiarize yourself with the science of logic, as it is the tool of philosophy. We also recommend gradually reading philosophical texts, starting with the easier ones or reading them alongside their commentaries. We are not sure which specific type of philosophy you are inclined towards, as there are many philosophical schools. Almost every philosopher, especially the later ones, has a unique school of thought and a different perspective from their peers. Islamic philosophy is also diverse, with schools such as the Peripatetic philosophers like Al-Farabi, Ibn Sina, and Ibn Rushd, and the Illuminative philosophers like Al-Suhrawardi and Sadr al-Din Shirazi, among others. Each type of philosophy has its own methodology and specific terminology, so it is important to consider this before starting your studies. Secondly, the souls of people after death go to a realm known as the Barzakh or the world of examples. We do not believe in the transmigration of souls and consider the belief in this absurd notion to be misguided and heretical. Thirdly, Allah, the Exalted, is the creator of everything, and it is impossible for Him to have a partner in His creation. All existence is His creation, and the beings are the effects of His creation. As for what you read regarding the similarity between cause and effect, that applies to natural causes and effects, and there is no similarity or correspondence between voluntary causes and effects. May you be successful in all good things.