I would emphasize that the control sensitivity of a basic trainer begins with the line spacing at the handle. You want an unresponsive feel at the endle, so the line spacing for a 1/2 A trainer should be about the same distance as your middle two fingers....an inch and a half or so. The same spacing at the bellcrank gives you a 1 to 1 ratio. Next, the elevator push rod needs to pivot as close as practical to the bell crank's pivot point...aim for the inner hole on a Carl Goldberg bellcrank.
Do not use "1/2A "control horns, use a medium or tall horn on the elevator. The total amount of elevator movement only needs to be 10 degrees either side of neutral if the CG of the plane is set at 20 - 25% of the wing chord. The idea is to have just enough pitch control to gradually take off, fly some laps and then have a easy time off allowing the plane to land. More control can be "dialed in" later, once the pilot gets bored with doing basic laps. APC sells a 6 x 2 pitch prop to help keep the lap times to a manageable pace.
The Goldberg Lil Wizard was the absolute easiest trainer I ever flew. It was well matched with a Cox .049 and a 6x2 prop to keep the speed down. It was a thrill to be able to fly on 26 foot long dacron lines at the time because my only other experience flying was with those awful RTF plastic planes that came with much shorter line.
Thanks to a very knowledgeable hobby shop owner in Auburn Washington , [Harvey Wagner]...he set me up with the "trainer package" that I described here.