It may sound pedantic but it is not an exaggeration to say that many Python-related questions asked on Blender forums can simply be answered by reading the API docs thoroughly.

Of course, these are not the easiest documents to read as they cover many topics and often it might not be clear where to start, so it might be a good idea to read them at least once in their entirety from start to finish. Not only will it give you some idea about the vast scope of the Blender API but it will also help you find specific subjects later on.