Personally, I bought a 3 bed single family home soon after starting my job and had two friends from college rent which covered my mortgage plus a little extra.

Then the rents would cover that payment plus the mortgage with cash left over.

I am new to rental appartment so wanted to get some advice, if I build a 7 unit appartment for $700,000, say mortgage of  $4000 per month.

Quote from @Dave Schimmels: What is a good way to get accurate rent comps with existing tenants based on the area?

Could you sell 1-10 of your existing properties and reinvest in one or two more lucrative opportunities?

I make around $110k+ per year, live off around $75K, have a mortgage ($1900/mo for rent, escrow, tax), around $40K in equity, and no other debt. 

Right now, the best offers around me are for some 1.3-4 million, that only generated around 100k per year gross, so there would be a high chance of not cash flowing, and paying money, especially with a commercial loan (these buildings have more than 4 units).I was thinking that although the rental itself does not generate money, I would be able to deduct the mortgage interest, and depreciation from my personal w2 income and would be net positive.

A successful rental property should offer positive cash flow, meaning your rental income should exceed your monthly expenses (mortgage, taxes, insurance, maintenance, etc.).To find the right tenants, ensure the property is priced competitively within the local rental market.

Does your mortgage include your property tax payments?

               $215K @ 2.65% rate to be paid offRental in area -                I can rent this for $2600/month and it will give $500 cash flow after mortgage and HOA.