If you want to move the property quickly and ensure income, seller financing seems more practical despite the tax trade-offs.

Training, do 5 to 10 deal analyses for practice, read a lot on this forum.  

Here are some key criteria for evaluating a Cost Segregation provider:-  Seek out a Certified Cost Segregation Professional- Consider their experience with tangible property regulations.

There are no laws, rules or regulations preventing any foreigner, American or otherwise, to buy property in CDMX or Mexico for that matter.If, by having success, you mean getting a profitable investment, I'm sure many American and other investors got that over the last few years (I personally haven't since I've focused my efforts on Mexico's beach markets, which are far better in my opinion.

Give something first - my example is simple - Can I cold call for you, I need to practice in this area anyways?

My county passed a new list of regulations last year.

Any tips for me or any best practices from fellow investors whose been in this industry for a while now?

Section 8  is a HUD-funded program but there are no universal regulations.

WELL, first check local and city regulations. 

I had just finished a course @ my local REIA, "How to find the hidden gems" & was EXCITED about putting it into practice right away to do a deal!!