Get organized:
The more organized your farm, the easier it is to manage. All of my devices have labels with an id. Some people use numbers, but my devices have their own names, emails, dob,etc. If something happens to a device, I can go to my binder and pull all the information on that device, Ex( os, model, email,app assignment) This information is very helpful when you have to replace a device. You just switch the information over instead of creating a new id. You should be creating new device IDs only when you add a new device to your farm.
Devices:
I use cheap phones. These phones will be abused, so you don't need to buy the latest and greatest. All of my phones were less than $30. If you have phones laying around that can connect to WIFI then you are in business. If the ESN is bad, you will still be able to farm. If the phone is hard locked(bricked), then no it will not work to farm. You can use damaged phones too.
I have phones with cracked screens, audio issues, and water damaged. I have purchased many phones my favorite is the LG Zone3. I bought them at my local dollar store for $24. I usually use "no contract" phones, because you can just go into the store and buy as many as you want. I started out with 5 phones, then I began farming hard, and eventually they began to buy my other phones, and that is where you want to be. Just spend a little money up front to get started, then have the operation pay the rest.
When starting your farm, build it so it can be expanded upon later. (Ignore the hanging bulb :)
