Phil Pustejovsky (sp?) has a great video on this. You can increase your cash flow by doing student or vacation rentals, renting by the room if it has many bedrooms, or if the law allows it there, doing a lease to own agreement. I am going to try that one next time a tenant moves out. You get a down payment which if they don't buy the house within the contract term, you get to keep. This increases your profits.
Also, this is a great way of selling a house without paying buyers OR sellers agent fees.