Ultimately I would like to build a large real estate portfolio.  

It seems like you already have a solid foundation to work from but some recommendations regarding BP:I highly recommend BP's Ultimate Beginner's Guide, it helps to form a general foundation in the industry.

Welcome @Anthony Shears May I suggest reading "Ultimate Beginner's Guide to REI"  This might point you in the right direction. 

No matter how or why the deal went south, you are ultimately the one that made the decision to pull the trigger and get involved in the project. 2.Forgive yourself and move on.

For me, ULTIMATE success equals cash flowing $10,000 per month off of rentals.

I actually ended up changing the due date back to the original/earlier date, and then ultimately getting rid of the tenant altogether.Now I don't have any tenants that pay late and it's so much less of headache. 

It will be an indication of their housekeeping skills and ultimately how he or she will treat your house.Verify employment.

We are thinking to try a flip next but ultimately, we are planning on getting more rentals, so the money will get used one way or another. 

Yes, ultimately I think flipping is what's I want to do because it's the most fun and challenging.

For my partnership, ultimately it was time to split because my partner no longer put forth any effort.