No real rules on which radios to use.
All you need is a radio that can receive and transmit signals and one that has about 14 channels.
There are a variety of manufactures and price ranges depending on your budget. Some brands out there include; Motorola, Cobra, Puxing, Wouxun and Yaesu. I personally use a Yaesu VX-7R.
You might also want to consider a headset of some kind so you don't give away your position.