comments:
For a 101, I’d suggest Leiden’s Online Introduction to Comparative Indo-European Linguistics From there, UT Austin has lots of resources through their Early Indo-European Online with structured lessons in many of the major ancient languages within the family. The lectures through Goettingen’s Ancient Indo-European Grammars Online are also worth a watch. It may be worth picking up a dedicated textbook like The Elements of Hittite, Sengoidelc, or Kuśinne Kantwo for a language that interests you alongside something more general like Fortson’s Indo-European Language and Culture : An Introduction. You’ll probably find studying Latin will help your Greek and Sanskrit etc, but there’s hobbyist stuff like Modern Indo-European that I’m less familiar with that might be more what you’re looking for as a coherent language to use in artistic projects