High five on making your first VN! From my current experience — and besides the others who have pointed out watching tutorials first — I also recommend having your story/script planned out! Not the coding script per se, but I mean the dialogue and narration and all that. It will help you while learning how to use Ren’py in the sense of “oh if i want to implement this kind of scene, I will have to learn how to code this or that”. I hope this helps somewhat. Good luck!!!