Homes that are flipped (bought solely for the purpose of immediate resale) cannot be sold on a 1031 exchange. The guidelines are somewhat fuzzy but typically the minimum amount of ownership needs to be 1 year or you need to be able to prove that the home was originally intended to be used as a rental and that circumstances dictated a change of mind.
If you can get going decent try to buy your rentals 10%-30% below market value, then sell via the 1031 exchange every year or two depending on your interpretation of the 1031 exchange guidlines. If done correctly you could have a paid off rental property in under 10 years all bought with tax free money.
You should also look into a self-directed IRA for the purchase of real estate
Eric Medemar