"Real Estate Investor" Is this a good strategy? What else could be done?

[Raul Ruvalcaba]

Hello,

We try to aim for properties around 80k... I give 20% down and get monthly payments of approximately $350.00 without tax and insurance. I am left with a debt of approximately 60k. 

However, I am not convince that this is the best strategy... In less than a year, we have acquired 3 properties... with the following mortgage payments 1) $350.00 (Rents for $750), 2) $333.00 ( Rents for $750), and 3) $515 (Rents for $1,100.00). 

For some reason, I feel like I over pay sometimes... However, I feel its better to have the money invested and earning money... In the long run, we will recover what we over paid.

The property taxes and insurance are paid with all the rents collected.

I am preparing to purchase another property... I just want to make sure I am not making serious mistakes along the way.

Is this the only investing strategy? What can I do to improve and make it better? 

Thank You