Pretty much the freehand approach. I sketch out what I want and figure what radius will fit in the space and go from there. On my branch line which has tighter radii than my mainline, I have Ribbonrail gauges for 28" and 30" radii which is the tightest I use on the branchline and use those to layout the curves. I want to make sure I don't go below 28" radius. It's not unusual for me to make changes on the fly from what I originally sketched out.
When I first began designing my current layout, I used software to draw plans for the early sections but I ended up going back to old fashioned graph paper, a compass, straight edge and a pencil to design the rest of the layout.
do you print out a plan and lay it down on the bench?
or do you locate key things and fill in with flex track?
greg - Philadelphia & Reading / Reading