First thing you've got to do is try to downplay the appearance of the big, bold, round muscle pattern. When I'm clipping heifers, 90% of what I do is sharpening lines and adding the appearance of additional length anywhere I can. This means doing things like taking more hair off the top of the shoulder, nearly shearing everything in front of the shoulder as well. Tail heads are different as well, with their purpose being to lengthen the hip and rump.
There are times you'll want to leave more hair too though, such as in the center of the top and belly. Also, making the legs more about shape rather than size is very important.
All in all, a good conservative rough out with emphasis on angularity and good lines will get you by just about anywhere except the highest levels. That way, you can clip her down tighter and more aggressively fairly soon for the next market class you enter in.