He tried to push a due diligence deadline to the closing date on his offer and then said he made a mistake and they went ahead with another property.

I  Am aggressive but don't want to make foolish mistakes by moving too fast. 

I made the mistake of applying for an unsecured LOC with Wells Fargo and they would only give me $35,000 which I didn't think was enough.  

The lawyer also made a huge mistake by not immediately ordering a warrant of eviction, thinking the tenant would actually leave.

The tenant is permitted to pay the difference,she is either making an honest mistake or lying to get cheaper rent.Tell her to pay the difference or you will move on to someone who will.Make her produce something in writing that you can verify.She can't of course so be prepared to move on to the next candidate.

Many mistakes new investors make is to skimp on their office equipment.

She says a day later that he is still worried that someone will mistakingly call the employer and he hasn't filled out our app. 

I just live here by mistake.

Something I'd be curious to hear more about are the "failures" or mistakes other investors have made.

I want to start early, so that I can learn as much as I can about real estate and minimize mistakes in the later parts of my life.