I have studied most of the concepts of Newtonian mechanics and understood the calculations and derivations involving the concerned formulae. I have a basic knowledge of calculus (differentiation of products along with differentiation of trigonometric, logarithmic, exponential and implicit functions as well as how to integrate them by parts and reverse u substitution), and an understanding of 3d vectors and complex numbers (in polar forms as well). Like most people, I'm experiencing moments of frustration very often nowadays because I frequently encounter questions which require a knowledge of relativity, which brings me to my question: Should I start learning relativity? My knowledge in Maths is not very extensive(as you must've gathered by now) and I've heard that GR is mostly maths and SR is conceptual, so if I start learning relativity, what should I start with? Does anyone know any good websites where I can learn the essential concepts and practice questions?