You could use an online service such as EzLandlords.com, download a generic template from your City/Municipality (Boulder actually has the Boulder Model Lease... it's a little quirky, but works), or best yet, work with a lawyer.  

I have a list of generic, "GOOD" review templates and I just copy and paste them into the review section of Airbnb.  

In answering your ‘supplemental’ question...

You can report that to the insurance co, too, and hopefully get a supplement.  

Hello all,I am a homeowner looking to supplement my income by purchasing a second home, preferably a duplex, and renting it out.

Thanks Eddie, I reviewed my contract and it looks pretty generic.

In this case, you walk into the sunset because your LLC has no assets, while the property owner loses his/her property and maybe faces their own liability if they don't have enough supplemental insurance? 

In terms of reasons not to invest: you find something illegal on an executor of a deal (I'm using generic terms to refer to any type of investment) or their strategy doesn't resonate with you or you don't agree with their deal analysis or the deal doesn't look attractive to you.

@Michael Volek My horribly generic advice:  pick a lane, swim in it, and stick do it.  

And being that you're just looking to supplement your $15K, you may be able to get what you're looking for.