That's a big subject with a lot of interactions involved----
But basically, all modern pattern designs have a symmetrical wing section, so the wing needs to be at a slight positive angle relative to the tailplane,to provide lift to defy gravity when the model is flying level and upright.
Sooo----set the model up on the bench so that it looks "right" in the side view, i.e. how you'd have it looking flying level.
Then set the tail,with the elevator absolutely neutral, at 0 degrees with your incidence meter.
Then set the wing at 0.25 to 0.75 degrees positive relative to the tail(Wing T/E lower thanWing L/E)
Use the lower figure if your model is at the light end of its possible weight range, and go higher if it's at the heavy end.
There's a lot more, re. C.of G., trimming for straight down lines, etc., but hope that's answered your question!