how much can i raise the rent on my tenant

[Larry King]

Hello, 

am new to investing, and managing property  looking for advice/guidance

1] I am trying to find out how much i can raise the rent on my tenant and how many days notice to give them.

I have a single family residence 3 bed 1 bath built 1930s tenant paying 1600 monthly signed one year lease july 2017. Residence located in an unincorporated area in south LA region of LA county zip code 90002. Never raised rent since they moved in 2017.

2] Are there property manager who consult for landlords to help them write lease agreement, or other paperwork for a fee of course without hiring them to manage the property. I have other questions to ask.

Thanks to any who respond.