If using this approach, ask for first and last months rent and consider offering them a small discount if they fulfill the lease terms. 

Sue K.What, specifically, are the rights the co-signer is obtaining in the agreement for the duties they are obligating themselves to fulfill.  

But why force the move because of what you perceive as a potential inability for a tenant to fulfill the rental agreement terms before giving them a chance to prove otherwise?

It looks like most of the options here (cozy/transunion/experien) recommend the tenant fulfilled screening versions which work great for one or two screens a year.  

M2M could mean the tenants have already lived there and fulfilled their lease.

I do something that some view as illegal, so I would advise anyone to view their local laws, customs, etc. i am a huge fan of "rewarding" the tenant for fulfilling their monthly obligation.

When you embark on you real estate empire building journey, you must ask yourself if your primary goal is to fix the societal problems you mentioned above, or if it is to make money.If your primary goal is to help others, you would be better off working with charities.  

We held the ex-girl friend responsible to fulfill the terms of the rental agreement. 

Defiantly do the routine screening of the students in addition to the full screening of co-signer including the full credit /background check.Based on the description of the tenant issues you had and the fact that they were students I would suggest that you did not fulfill your responsibilities as a landlord.

I would add that you should find an attorney for your team to review your contracts sooner than later in your investing career, and they may be able to further explain the ramifications of a tenant not fulfilling their end of the rental agreement.