Start on the back cylinder. By the time you have it done you will be able to do the front one without having to be able to see your every move.
stumper, we are talking about adjusting valves.Not peeing in the dark

but yes the back one will get you familiar with what goes on in the front.Just put some lite oil on the gauge and adjust the valves til you can still pull the gauge out with some resistance.Hand on to the valve adjuster when you tighten the locking nut back up