Memorize the appendix of D10.8. When I took it a significant portion of the real technical portions of the test dealt with somewhat obscure PWHT principles of stainless steels. Know your NDE inside and out. Good luck, it is a very tough test!
The AWS provides a list of recommended references it your application form.
Part B is based on B2.1 and Part A is based on the references. There will be questions on welding processes, metallurgy, Stainless Steel, NDT methods, SNT-TC-1A, and ISO 9000 related questions that address quality systems. In round numbers; 200 questions in total.
Best advise is to read the references.
Good luck
Al