Securing a Contractor(s) for a foreclosure/ sherriff sale flip

[Kellie Powell]

I feel like I might be putting the cart before the horse.  

I intend to buy a home at a Sherriff sale (foreclosure).  I want to have a contractor available to begin work, if we are the winning bidders.  However, how do I have a contractor lined up if I can't actually even go inside the property to be able to specifically say what work is needed? I have some photos of the interior and have a general idea...like removing paneling and replacing with drywall.  New light fixtures, new kitchen.  Typical stuff.  How does a contractor commit to being available for a project that may not even happen.  I don't want to buy a house and then not be able to find a contractor available to do the work needed.  

What am I missing here?  What are the right steps to take in the right order?