Few questions about rentals

[Sean Gallagher]

How profitable is the rental business? I've been looking over some threads here and see that percents are used a lot when dealing with duplex's/ plan on renting out a building. I'm not too certain on the percents and to be honest am a bit confused on how to tell if the property will be profitable. Like how much do you guys know to charge monthly? How come you just say take 10% for this this and this. Why don't you just add everything up , figure out the percentage that is of the monthly cost and then add a percent or 2... What is it like 50% of monthly charge? My problem is that I'm just starting out and have no clue what is involved/ what bills need to be paid by the landlord and what by the tenant. I'm very willing to learn, most of the threads I read it seems that the thread starter already has something going. Not me, but someday I hope to have many/ a nice size complex. How reliable are rentals? I'm going to keep clicking on post and reading. Im 19 and want to see how much i can accomplish by the age 30. I have a long ways to go, I've been talking to business men lately, and it helps.. but one told me he has been there before with rentals and it didnt work out for him.. But my vision is that i see a lot of successful people on here with rentals so whats the problem? Everyone needs a home right? I mentioned a lot in my post, if someone can touch on atleast 1 thing for me it would be greatly appreciated.

Ps how much cash flow is attainable with a rental? I guess it help once it is paid off huh? please help, thanks guys