It's been a long time since I wrote that guide - must be coming on for 10 years ago now
There's a few more that have been mentioned so far already. Play around with light and dark. If you shoot through a dark area and place the target in the light, it can make the target appear closer than it is, especially if you use a light coloured faceplate and the opposite is also true - if you're shooting through a light area into a dark area that tends to make the target look further away.
Most of the tricks though are things that are peculiar to your ground, so it pays to experiment.
It's no good just setting a target in an area that might cause you to misrange either, you need to double that up with a target that will mean you'll miss if you get the range wrong. So the example above about bracketting a 30mm kill at 38yds gives the same answer as bracketting a 35mm at 45yds. If you couple that little nugget by putting the 38 yarder out in a position that makes it look further as well.
If a target looks about the right distance as the distance you've bracketted it at you're more likely to aim in the wrong place
Personally, I love to see a course that's had lots of thought put into it - helping to set out courses yourself really helps you to appreciate a good course. Some of them are nothing short of a work of art, but you have to have course setting experience to fully appreciate them.