Yes, be VERY careful. if you're getting up towards Green you will be dealing with over 100V DC and that stuff can kill you stone dead.
Might even be worthwhile getting some insulating gloves.
I do wear rubber gloves, but thicker ones would be prudent.
This reminds me of my days in grad school. I worked in a lab where we did high energy electron bombardment with alot of homemade gear. There were very high voltage sources all over the place and accidents happen. My professor said always keep one hand in your pocket and I thought he was kidding.. but he was serious.
He said the electricity would go through your arm to the floor vs your chest if you hand was in your pocket. Through arm wouldnt kill you, vs through torso would (only takes a few mA to stop your heart).
He put this into practice once by accident and the current actually blew a hole out the bottom of his shoe....
I never felt safe there...
I take alot of precations, and using a grounded power source for the current makes me feel safer than a DIY one too... but ya safety is important!