The textbook answer is to use an incidence meter -- and I do use one. On the subject of the incidence meter, however, I build a lot of airplanes (not just one or two a year: sometimes more than a couple a month) so to me the incidence meter is worth way more than the $3 I paid for it at a swap meet. For a beginner who may only build one or two planes in the next year or two, the $25 to $35 retail that the meter will probably cost may be a bit expensive.

As it turns out, a bullet level ($2 to $4 from Sears or any home improvement store) is not a bad tool to have. Geometry will tell you that to get the 1 degree incidence needed, you can support your fuselage such that the stab is level, then set the wing support rails so that they're level side to side and dropped about 1/16" in the front (check the plans for an exact measurement: you should be quite exact on this one). Not really too much magic involved at all... just make sure that the fuselage is held in place firmly when you do this (regarless of whether you use an incidence meter or a level).