I found an apartment for sale with an assumable loan.

Purchase the first one cash (to mitigate risk) and the second property with a loan.

I paid $600k and got a local bank to loan 75% for 5-years at 3.85%. 

You will need to make sure you meet all the lender's requirements if you are planning to buy with a loan. 2.

I loaned to an LLC for a flip.

Draft precise agreements outlining loan terms, manage risk by diversifying investments, and build relationships with real estate professionals.

Also, compared to a traditional loan (i.e., conventional, FHA, etc.) for a primary residence your rate/points options are going to be higher for an investment.

Conventional Investment loan.

An original purchase loan was taken in 1998, which was refinanced in 2004, and then again in 2005.

This way the commissions get rolled into the loan (in most cases) and buyers (most of whom are using financing) don't have to pay their agents commission out of pocket in addition to their down payment.