The Falcon T50 does require you to rangefind by always approaching the mark from the same direction. Don't hunt the sidewheel back and forth as you might with a Nikko. It doesn't matter whether you range close to far or far to close so long as you are consistent.
When doing the sidewheel markings, I find it best not to do them in sequence. I will do 55 yards then maybe 25 then go back to 50 and perhaps follow that with 15, and so on. Being a nerd, I then plot a graph of the distances between the marks, and these distances should fall on a smooth curve. If they don't, it's usually simple to spot the ringer, so I go back and check that point over and over again.
If you've adjusted the eyepiece lens to make sure the ret is sharp, then you won't have to choose between the ret and the image. Do the eyepiece adjustment before anything else, get it right and tape it up, then do the range markings.
Hope this helps. Good scopes for the money.