Looking for some education in tax sales

[Felix Gutierrez]

Hello all ... I am just getting started with investing and had an idea which I am sure is not original but need to hone my skills so looking for some guidance. 

So here is my plan. I go and look an the tax sales list and find tax delinquent property that are going to be coming to auction but have not yet been listed . I do some research and get the total amount needed to get the property up to date. Then I want to then contact the county and see what the total amount is to clear the debt. Then I figure out what the condition of the home is and make an all cash offer to the person to sign a quitclaim document assigning the property to me. Once that’s done I can either keep the tenant in the property .. and collect the rent or find a buyer and usually mark it up 20-30% . Is this the right thinking or am I missing something?