@Stephen Masek My brother @Alexander Budka and I have combined 13 years of experience owning, managing, leasing and brokering NNN deals. Honestly, it may sound overly simple, but the number one aspect to consider when buying NNN deals is the classic RE investment aphorism: location, location, location. Other things to consider are the strength of the actual entity the lease is signed with (and make sure to thoroughly understand leases!). Evaluating rent-to-sales ratios can give insight into the performance of the business. Definitely analyze comparable sales and lease comps in the area.
NNN acquisition criteria really varies depending on your risk appetite. You're probably looking at NNN nationwide I presume? A slightly higher cap rate of 6%-7% out of state vs. a 4.5-5% cap rate in CA isn't that great of a difference in the long term. NNN deals located in in-fill, highly populated, growing areas have a much brighter future in terms of re-leasing potential if/when a tenant decides to vacate, versus some random property in Nowheresville, Midwest that has very limited future re-leasing potential.
Now is actually a great time to buy NNN deals. Because the uncertain interest rate environment, NNN sellers are more likely to be flexible on pricing as the asset class is closely correlated with interest rates, which are on the rise, meaning its becoming more of a buyers market out there.