If you have a powered sharpening system, hell yes, practice on a cheap knife first. I personally don't see the need for a "practice blade" when hand sharpening, unless your main knife is of such stern material that it takes a long time to sharpen. When you're practicing you want to see quick results. SR77 is a very tough steel, but it's not terribly hard, and it sharpens easily.

When you're sharpening by hand, you are removing incredibly small amounts of metal per time, and you can easily stop and check to see what's going on. A good knife will last decades of hard use; something massively overbuilt like a Busse family knife will outlive you, the way most of use them.

Anyway. Just work slowly and stop to check your work often. It's really hard to "ruin" a knife by hand sharpening, if you just pay attention to what's going on.

(Funny story. I have a friend who asked me to sharpen a knife that her father had given her when she was a young girl. She admitted that she often used her knife to dig into the ground. The edge was totally non-existant; duller than a butter knife. I brought it back to slicing paper in five minutes on a diamond stone... Really hard to "ruin" a knife. If it's still in one piece, it can be brought back.)