In reply to @FarmCave:
I've found the easiest way for me to set is to have one specifice move in mind that I want to set (say a heel hook) and then keep that in mind for the duration.
I then set the start move, keep it reasonable so that pulling on isnt horrendous. I'll then pull on and hold the start position to get a feel for it, and figure out roughly where I want to be going next. Through some holds up in that general direction, and start thinking about trying to force certain moves.
I'll set most of the route by just kind of throwing holds onto the wall in what seems like a reasonable orientation and location, and then start tweaking.
My hold set is quite limited (and I'm the only one that climbs on my wall, so can set for my height - not really best practice but it works for me) so I'll make the most of rotating holds or having them at funny angle to vary the difficulty.
I've found that the most enjoyable way to gauge difficulty when setting is to get on each move individually, and just try and hold the position for a few seconds, but be pretty much unable to move onto the next move, but this possibly wont work if you're setting for climbers of varying ability.
Of course the other approach is a spray wall (I dont particularly enjoy these) or attempting to recreate classic boulders (probably very much depends on the hold sets you have and the way your wall is layed out.
Happy to chat more or exchange ideas with you (or anyone else for that matter) if you want to PM me.