Is it right that when I buy a tax lien certificate in GA I get a 20% return even if the person pays it the next day?  

Interesting, Darren, my definition is very close to yours, but I'd say there is another important element, the quality of the information given.To me, the derogatory use of the term is applied to those that add fluff, exaggerations, aspects that while may be technically correct but are highly improbable to replicate or simply put out bad advice with no consideration to ethical issues.I make that distinction because, some professor in some university teaching a real estate course or some instructor in a state approved real estate school for agents isn't a guru, they are teachers and instructors.The difference in being a non-guru teacher is two fold, 1. the materials taught are compliant with rules, regulations, laws, accepted in practice and are based in sound applications of the business; and 2. they are qualified by education and experience, by education that has some professional level that is determined by proof of their mastering a level of knowledge, testing and degrees earned or certifications by proper authorities in the industry or academia.

If you're handy, you can ask the contractor to bid for very basic interior finishes (enough to get your certificate of occupancy) and then you can DIY a lot of cosmetic upgrades later on (things like painting, adding backsplashes, flooring upgrades, putting in nicer fixtures, etc.).

I live in Baltimore Maryland and interested in buying tax lien certificates...

I will reply but I doubt I will be of much help.Every state has different statutes regarding how certificates are created, acquired, effective periods, minimum certificate age required to apply for a tax deed, certificate expiration age, etc.I recommend that you post what states you are interested in purchasing certificates and hopefully individuals who have acquired certificates in these states will respond.Your strategies will dictate your operating costs. 

If I pay a lawyer $200 an hour to draw up certificate of sale, am I just spinning my wheels because the mortgagee will likely redeem?  

It took us quite few weeks to go through all these procedures to reverse original assumption.As for living/renting - not the case also, it's illegal to live in the property until you obtain clear POS and rental certificate from the city.These POS inspections slowly getting admitted to be illegal practice (Bedford Hts won the litigation and get all these fees back) but majority of cities in East suburbs are affected.Obviously, it doesn't apply to East Cleveland or inner city - you can still buy houses for $100 and sell for $1K ;)

Such an economical jester can reap great rewards.My good tenants receive restaurant gift certificates during December with a thank you letter.

Taxes - make sure they're paid, know the difference between tax certificates and tax deeds.

Today, there aren't any in NY near me.To buy something, you do have to fill out their certification form.