In two years that 600k could have earned $61500 in a pretty conservative investment or $126k in a full market risk index or account(major index). 

Instead, ready "Richest Man in Babylon" and "How I Turned $1,000 into a Million in Real Estate in My Spare Time" (the original version by William Nickerson), and begin putting together a definite conservative plan to build a real estate investment business with low risk of having to declare bankruptcy.  

Just be conservative with all your calculations.

I haven't had any inspections or even made an offer on the property yet so all of these numbers are very rough conservative estimates, and I'm trying to plan for the worst.

@Andy Cross Union bank is more conservative and they like to see conventional applications, you have to show proof to everything unlike Chase bank & other big banks where you can set up your account with a couple of documents and signatures..

When using the BP Rental Property Calculator to evaluate potential deals, I know that I’m being conservative with my numbers (because I really don't want to mess up my first deal!)

Lenders want to stay in a conservative underwriting box especially for low interest rates so they can stand up to an audit by the OCC as making sound loans on the market.   

We analyzed based on the ARV of $151k, which we believe is being conservative in its area.

If you deployed your strategy locking on 30 yr terms, you can always pay it down shorter if you desire to be more conservative later but 5yrs from now if interested rates are much higher you might be kicking yourself.

You can budget around 4% of the sale price to cover these.This is a conservative formula.