You could start with his most famous work, 'The Silence of the Lambs', and then move on to 'Red Dragon' and 'Hannibal'. That's a common and enjoyable sequence.
I'd suggest starting from his early works like 'Black Sunday' and then progressing to the more well-known ones like 'The Silence of the Lambs' and its sequels. This way, you can trace the evolution of his writing style and storylines.
A good order could be to begin with 'The Silence of the Lambs', followed by 'Hannibal' and then 'Red Dragon'. But it really depends on your personal preferences. Some people like to read them in the order they were published.