Can I raise rent that has been to low for a long time. Canton, OH

[Jason Campbell]

I have a friend that owns a number of single family homes she rents very cheap. My friend is going through a divorce and has asked me to help manage her properties. The first thing I noticed is that she is renting her houses out way to cheap compared to similar rentals in the area. For instance, one home is a one bedroom, one bath house on half an acre that she rents for $400/mo all utilities included except electric. Similar homes rent for $550 to $650.

All of her properties are rented and the people have been there for a long time. None of her properties have leases and she has never required a security deposit. 

My questions are: 

1) Can I write up a lease with a rent increase to the market standards? Is there a cap on how much I can increase the rent if they never had a lease to being with?

2) Can I include in the new lease agreement a security deposit? How about a last months rent?

All of the properties are located in the area of Canton Ohio. Any advice would be very much appreciated as I am new to this line of work. I'm been trying to do some research about this, but am having a hard time finding anything helpful, because of the renters never having a lease to being with. 

Thank you to all who respond :)