US visitors visas for my Chinese wife

Hi all you experts out there!!! I am looking for information on what is the most reliable way and what documents we need to submit in order to obtain visitors visas for my wife so that we can travel 2ogether to US.
My wife (Chinese passport holder) has been living in the UK for approx. 7 years on UK student visas; she has been married to me for the past 2 years and as a result of it she holds UK Residence Permit as a Family Member of EEA National attached to her passport. She does not work and she completed her university degree already. We live together in a rented apartment, I have a stable job and my wife also gets financial support from family.
I have just scheduled an tourist visa appointment for her for October in London. Could anyone advise what documents should we prepare that would guarantee isuance of visitor visa in our case (we are able to get invitation letter from my former class-mate who lives in US as well as satisfactory bank statements, marriage certificates, references from friends etc...)

Thanks for all your help.

See also B-2 Visa (Holiday visa) and

Additional Administrative Processing wrote:Chinese, Russian & Vietnamese nationals

Applicants, regardless of sex who are aged 16 and over are also required to complete a supplemental nonimmigrant visa application form DS-157.

Applying for a Visitor Visa? and
Visa Denials.