I use the old fashioned two person method when I have a helper around. I have managed for years to flush and bleed at every pad change without a helper when my kids were too little to be of any help in job like this.
I run the hose from the caliper bleed screw into a jar (after putting a box end wrench over the bleed screw nipple hex), cover the end of the hose with fluid, and then loosen the bleed screw to push the pad/cylinder back without forcing old blackened brake fluid into the system. This usually fills the hose and then some, and then I tighten the bleed screw. Change the old pad with a new one. Like someone already noted, make sure the fluid reservoir is full of new, clean brake fluid. I use Castrol GTX LMA fluid.
I do the other pad, same sequence, and then flush the caliper and line. With the end of the hose covered with fluid, I loosen the bleed screw again, and pump the brake myself. After a few strokes, I tightened the bleed screw, and checked the brakes for sponginess. If it is not nice and firm, refill the reservoir and do the process again. If you don't open the bleed screw to the point where you get no pressure build up (resistance on the downstroke) when you pump the pedal, you get enough fluid to fill the threads on the downstroke and then in the upstroke of the brake pedal the threads stay sealed.
Procedure has worked fine for nearly twenty years. Still does, but I get help these days from my two sons. Good learning experience for them as I believe they will have cars with hydraulic brakes for years to come. Jim
1986 Euro 190E 2.3-16 (291,000 miles),
1998 E300D TurboDiesel, 231,000 miles -purchased with 45,000,
1988 300E 5-speed 252,000 miles,
1983 240D 4-speed, purchased w/136,000, now with 222,000 miles.
2009 ML320CDI Bluetec, 89,000 miles
1971 220D (250,000 miles plus, sold to father-in-law),
1975 240D (245,000 miles - died of body rot),
1991 350SD (176,560 miles, weakest Benz I have owned),
1999 C230 Sport (45,400 miles),
1982 240D (321,000 miles, put to sleep)