Large banks like Wells Fargo,etc. have REO departments and use agents so unless you are buying in bulk (like 50 properties,etc.) they won't usually talk to you but refer you to the agent they have assigned that listing to.
You can go to local and regional small to mid size banks where they might have one collection manager handling their REO. Sometimes you can be put on a mailing list for those properties.
Usually the local and regional banks also use a broker like myself to market the properties.
I typically do not like auctions as the goal is to drive up the price with multiple bidders. Some allow online bidding which I like because I don't have to go somewhere and take a whole day to bid on something that might not work out.
Buying a foreclosure at the courthouse steps will depend if you are in a redemption state or not.Usually most properties at the steps are over leveraged so it's better to wait for the bank to foreclose and get it ready for REO sale.
When looking at REO "cash is king". A big point though is condition of the property. The most money to be made is in repairs needed.
Example 1 : REO 2 year sold that just needs carpet priced at 100k.You offer 70k cash but regular homebuyers like the property as well and offer 95k to which you lose out. The asset managers love cash but will take a finance offer if it nets them more money.
Example 2 : Property needs extensive repairs.Most homebuyers like the low price of 60k but cannot get financed because they want to buy with FHA loan.You come in and offer 45k cash with a short inspection period. You purchase and sink 20k into it and now the property ARV value is 120k and you have great cashflow.
Sometimes you can buy a move in property for cheap but most of the time will lose out to home buyers offering closer to asking.