I learned to shear by helping the guy who used to shear mine. He has bad hips so the smaller ones were harder for him to bend down to. He showed me how to shear blind from the breast up to the neck with my hand shears and the rest was easy after that terrifying experience. I refused to start with electric shears and only used my electric shears for the first time this year - still find I get a better finish with hand shears. Best tip for you would be to keep the shears flat to the skin and keep the skin taut if possible.
A good shearer can shear blind and work by feel, you have to for some areas as the fleece just obscures the shears completely. I wouldn't have confidence in a shearer who said the blacks were harder to do personally, it makes no difference at all.
See if you can get some 'hands on' with someone who does their own and just go for it. You will get neater and faster as the years go by. I just do a couple a day, it's too hard on my hands and hips otherwise and as long as they all get done what does it matter.