The client will have to sign a document at closing that no funds have been paid out that are not reflected on the HUD.

I'm currently planning on hand addressing all envelopes (my list is about 400 properties, starting small) and signing all the letters.

Go to REI meetup groups, put up some bandit signs, do a direct mail campaign, start calling people, go door knocking, just do something to get yourself out of your comfort zone and start working.

It really helped me get a good foundation and also helped me to select my target area to focus on. 

Should I include a contingency that says current tenants must sign a lease with me at or before closing, or is this going to kill the offer? 

@Peter Arroyo I’m sure you’ve already planned for this, but be very cautious on the tenants you select, especially if students.

Some common mistakes are trying to go cheap, not vetting out contractors, paying contractors too much up front, not having contractors sign a contract when you accept their bid, not having enough of a cushion for unexpected repairs (there will always be something)

In may of this year I was going to increase the rent but I gave him a chose to pay $50 more per month or if he signed a two year contract I would keep the rent at $850/month.

They provided security upon lease signing. 

Most importantly, to get a homestead exemption, you usually have to sign something attesting to the fact that it’s your primary residence, and you definitely wouldn’t want to falsify that form.