I also like the speciality paint store (where I go Ben Moore, for example) just for  consistent service and expertise (hit or miss at the big box there).Then hard to beat the old school prep with tsp and  a good sponge mop (just damp) and rinse with clean water (damps sponge mop)...and primer for major color changes or spots  and stains..The good paint in luster you can clean also makes turnarounds easy...clean the walls (as mentioned) and you may only have to touch up..Finally, if you can go with one color/brand for the interiors of your rentals you will save time trying to match color or organize endless paints in your garage...best of luck

Do everything you can to leverage your time to gain experience as opposed to looking for the deal or the money right now.Starting out of the gate doing a no money down deal is possible but it's more the exception than the rule in my opinion.If you are already reading and do the research then you don't need much more specific advice you just have to continue taking action every day, and continue working hard to leverage your time, where you can gain experience.There are seemingly endless possibilities to get started, but if you keep seeking knowledge & experience, you will figure out your way to make it work.