Investment Property Mortgage Pre-Approvals?

[Justin Strait]

One of the things I've seen when it comes to starting in the REI arena is getting pre-approved for mortgage. In my consult with Rent-to-Retirement, my consultant Adam made the same point.

So as far as investment properties go what strategies do folks use? RTR has a preferred lender but I'm also looking at PenFed as I know they are one of the most competitive out there, but both were asking about loan size, property cost, and expected rent. 

For a pre-approval do most of you just put estimates or find a property and use those numbers? I'm looking at several property options and not sure what strategy to use here.