Reading this little book gives you an ideal introduction to William Blake's values and writing style.
Rusty Shell is a long term scholar of Blake. His blog on MHH gave us a good, detailed, down-to-earth introduction to the early Blake. Read it and if you're really interested in MHH you'll find a bonus in the shape of a PDF (file), essentially a lesson plan for a class in William Blake's famous book.
If you want to go straight to MHH click on this site.
If you have questions, use the comment option.