Go for small counties that do not have as much competition as the large ones. thats were I would start and thats where my Dad would buy 100 plus props a year at tax sale.Most of the online bids can be done from the comfort of your home and you are able to preset your max bid and the system can simultaneously bid for you on all properties across all counties at once, so that may only apply to in person auction.

Here's a list to give you an idea:Startup Costs:Down PaymentClosing CostsProperty InspectionAppraisal FeeProperty InsuranceInitial Repairs and RenovationsEmergency FundOngoing Expenses:Mortgage PaymentsProperty TaxesUtilitiesProperty Management FeesInsurance PremiumsMaintenance and RepairsVacancy CostsProperty DepreciationLegal and Accounting FeesRemember that these costs can vary based on factors like location, property type, and personal preferences.

The only person I would seller finance to is a solid long term tenenat, who has kept the property well over the years.

It may be the same person if they have the given experience and knowledge.

I find when people have no true personal investment they generally don't care.

I wouldn't charge more for rent if it was a family of 4 vs a couple or charge less if it was one person in a 2 bedroom home. 

@Matthew Meizis - I have some templates that I have used personally.

So, they might give you pointers about what criteria you need to meet for them to loan to you, because you'll be a responsible person.  

Probably a rare person that can answer that or maybe even any of the real differences. 

Do you have any sort of personal relationship with the investors or are they strangers?