putting offereing on the table?

I read many emails and Im looking at places in Baltimore and I joined local REIA in NYC that tours down there its a question I will ask them at the next meeting. but you folks,

What is the best method to offer to wholesaler or to a stressful homeowner that wants to unload thieir home at a bargain basement price? I know you offer cash but what about the rest?
DO I offer several thousand upfront and get pre-approved?

these are house in 30,000 needing repairs up to 20,000 or homes in the 50-60000 range needed some repairs in not so good neighborhoods but has some character and potential.??

I thank all the senior members for their knowledge answering newbies like me.

Cash and the ability to close fast, gets attention. However, more importantly, you need to have an exit strategy. If these houses are in bad areas, how do you plan to sell them? Just make sure you have that question answer first.