Need help with schematic

I am a photographer who has gotten into video and timelapse. I recently built a camera slider with two 12V DC precision gear motors.

I want to use an Arduino Uno to control the speed and direction of the two motors. After speaking with the guys at Jaycon systems, I have ended up with the Arduino Uno and the Ardumoto V2 shield. All the specs work out (at least on paper) for power supply and demand.

I also want to build a menu system into the Arduino, controllable by the SainSmart LCD shield with "select", "up", "down", "left", "right", and "reset" buttons. Yes, I know this is a project all to itself, but this is my long term goal. Getting it working to some degree would be a great accomplishment.

Ideally, I want to be able to go to my location, setup, select the parameters I want and hit "Go".

I'm hoping some of you electronics geniuses here can help me map out the schematic to get the Arduino, LCD, Ardumoto, gear motors and applicable power sources and playing together.

My experience thus far with the Arduino is watching some Jeremy Blum tutorials on Youtube and making LEDs blink when I want them to. Please forgive my newbness.

Here are the gear motors I have.

Well the basic schematic is 12V supply to relevant screw-terminals on the shield, the two motors to their relevant screw terminals on the shield, plug shield into Arduino (which will need power somehow - this could be derived from the 12V motor supply but that can present issues if that is too noisy or overloaded by the motors). Decoupling for the motor supply is probably the cylindrical electrolytic on the shield, so that all looks good.

Ensure the 12V supply polarity to the shield is correct(!)

Those motors will need PWM drive, ramping up from 0 (don't directly set to 255, that will strain the supply and be very rough on the gears). I've got a similar (but 600rpm) gear motor and it runs very smoothly at low drive levels...

Have a search around these forums for LM298 examples. When first testing I recommend using a weakish power supply for the motors (perhaps 4 x AA's might do), check all is well before moving to the proper supply - a little paranoia at the right time can prevent silly mistakes.

Thanks for the reply Mark. I'll see what I can find out about separating the 12V for the motors from the power to the Arduino. Any idea how to implement the LCD panel?