This book is how I started calisthenics. I cant imagine a better one out there. It has three sections, beginner, intermediate advanced. Each section has one page for every exercise with easier ad harder modifications then daily programs for an entire month. So it has a 3 months beginner to advanced program. When I finished it i simply started again but with a 5kg weight vest and 2 5kg dumbells to carry during leg exercises. It comfortably transitions you from pushups to archer pushups to one arm pushups. But some exercises when i reached the last month i needed to watch youtube videos and train for them separately to achieve them. For example in the last month it tells you on some days to do a 10 sec front lever hold. I couldnt do that so i did the easier modification and watched youtube tutorials and did separate trainings. The programs are literally perfect for endurance, hypertrophy and switches between muscle groups to rest them and not get injured. Trust me, you will not regret a single cent spent on it.
Buying a door bar is essential. I got my perfectly good one for 10 USD. A calisthenics pro i follow on insta was asked “can i train calisthenics without a bar” and he answered “can you play football without a ball” which in my experience is 100% accurate Also I would recommend buying this book https://www.amazon.com/Bodyweight-Workouts-Men-Anywhere-Exercises/dp/146544145X I started my calisthenics journey with it. It contains a 3 months program starting beginner, intermediate then advanced. There’s easier and harder variations for each exercise. This book can keep you going for a full year. After the first 3 months repeat but with harder variations then again but with a weight vest and so on. If you cant afford the book then I would search for free programs on youtube. Dont look for random different videos but find a program by one creator and stick to it. A good plan and consistency is key. Also you should warmup (ropejump is excellent) before every workout and stretch for flexibility after.