You can get some really great profit margins, but understandably there is headache... well, for a newbie, what kind of headaches are we talking about?

HELOCs are based on Prime Rate plus a margin.

Since I'm able to find deals that have such a big, obvious value and profit margin built into them, I'm able to list and sell them for a very cheap price and still make a good profit (and the properties basically sell themselves). i.e. - My shortcomings in salesmanship are easily overcomeable because I've mastered a different part of the acquisition process - one that mostly negates the need for me to be a master salesman... does that make sense?

I flip and my friends who are REI also seeing shrinking profit margins not only due to rising material and labor costs but also the loss of multiple bids.However, with any market there are locations still commanding high dollar.

See if being a landlord is for you, and there is a lot more margin for error on a long term buy and hold. 

One of the biggest mistakes I have seen less experienced investors do when choosing their first one or two flips is thinking they can save a lot of money by doing a lot of the repair or upgrading working on their own compared with paying a licensed contractor to do the work and mainly because a person doing the work themselves are not as experienced at doing good quality work and frequently will take a lot, a lot, a lot longer to get the work done and if you are financing your deal they you will end up paying a lot more in finance interest and still maybe end up with marginal instead of good quality work and you are only delaying the date for flipping , reselling, or being able to get a property rented.

There are better margins elsewhere, IMO. 

The estimated mortgage is cheap enough that even if I didn't have any tenants, it wouldn't really be a financial burden, and would actually be only marginally more expensive than renting commercial space for my growing business.

Honestly, I would much rather take a low cash flow deal in an attractive market than a marginally higher cash flow deal in a secondary/tertiary market.

Lay the numbers out, so they understand why the profit margin wouldn’t be enough.Similarly, if there are other reasons, like high crime areas or poor school districts, let them know.