I am also a R/E investor as well with multiple properties and continuing to grow and scale.

I would say this was the least organized BPCon (no cevent App, poor email distribution, my workshop that was $300 had about 20% attendance rate) I have been to, with the worse room problems (both ac and hot water problems in my room), and the hurricane issue (they cancelled the meal but many of the restaurants required reservations that we did not make because we were expecting the meal), and in my opinion worse keynote speakers even when one was a repeat (I like David Greene keynotes, but …), I enjoyed this BPCon more than the others I attended. 

How would I do that - send them a formal invoice or request, or can it be less formal like a simple email? 

Block her phone number and email.

Great news is when you get a deal there the spread is usually solid, bad news is many of the traditional marketing tactics don't work very well (at least in NYC where you cant cold call, PPC & PPL is really expensive and I don't know anyone who does well with direct mail).

By simplicity I mean, it becomes important to determine WHEN a payment is made.For example, if a tenant is mailing you a money order is the payment made when its mailed?

I was hesitant about joining the group because I've never had good luck with forums and web groups.  

Quote from @Scott E.: If I read your post correctly, you are currently running your guest house as a STR, but you do not currently have proper insurance in place.

Here are a few tips to help you score that first deal:Network: Join local real estate groups and online forums like BiggerPockets to connect with other investors.Find Motivated Sellers: Look for distressed properties and consider sending direct mail to homeowners facing tough situations.Research the Market: Know your area’s property values by analyzing comparable sales using sites like Zillow or Redfin.Craft Compelling Offers: Highlight the benefits of a quick sale to sellers and consider a solid earnest money deposit to show you’re serious.Market Yourself: Use social media to share your journey and post flyers in local spots to attract leads.Stay Persistent: Rejection is part of the process, so learn from it and keep refining your approach.With your big business mindset and hard work, you’ll make it happen!

., "East Basin", or “E-Basin”) separately if required by the system.