Jana, congratulations on taking action and being in front of the homeowner. I suggest that you not be the one speaking to the bank. You are the investor making the offer on the property. Banks generally require that a realtor be involved. The realtor would be the contact with the bank, and also usually prepare the short sale package; which will includes a hardship letter, financials and tax returns, and a short sale form usually specific to that bank.
As @Anson Young mentioned you want help if you are new to the short sale business; as it is more involved and time consuming than other strategies, but can also be very rewarding. You want a realtor VERY familiar with short sales and who is an effective negotiator, or I think better yet a third party short sale negotiator. You do want to look at your resale numbers to determine your offer price and want to start with a fairly low offer, (knowing that it is more difficult to negotiate discounts with the banks in this low inventory environment) and get it under contract with the homeowner. States differ on short sale contract requirements but most do have a specific short sale contract or short sale addendum - your realtor listing agent should know what is required. Although help is suggested here it is not rocket science and can be done with patience and perseverance.