I would recommend if you are starting out, either narrow down your definition of where and the type of property you want to invest and find the investor to fund it, or the type of investor you're looking for then seek the properties they will invest in.

What type of foundation is it?

Welcome Abbas,What type of REI are you looking to focus on?

If a beginner buys TDs as described in this post, and they yield 10.5%, what type of losses should be expected over the long run? 

Make sure to verify all information and ideally speak with an experienced investor who acquires in the respective state before proceeding. 

That seems logical - The way a seller financning transaction "should" go is the same as any other type of financing.

I'm looking to pivot into that type of strategy here soon! 

Just read some actual real life publications of this happening in the San Bernadino County California so this type of project is definitely possible.

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.

I've been doing BRRRR type deals in the midwest for the last few years.