Increasing rents for my tenants

[Nicholas M.]

Im trying to increase the rents of the tenants living in my multi-family. The rents are $300 under market. I just bought my first multi-family and am new to real estate. I was wondering...how do I go about increasing the rent of one of my units? I live in one half. Do I just send them a text that we need to meet up so i can tell them rent is increasing? Do I make a new lease and then tell them they need to sign it? As experienced real estate investors whats the best route that I can go about this process in the most professional way??? i obviously wanna go to market rent but at the same time I have ZERO experience. Do I start out at $50 a month till market or what? 

-Thanks